What are some popular types of gemstones?

Gemstones fall into two broad categories: precious and semi-precious. Despite their name, precious gemstones are not necessarily the rarest or most expensive stones but rather the most sought-after and valued overall. The most popular precious gemstones are known as the big four: sapphires, rubies, emeralds, and diamonds. Among the others are opals and pearls. Practically all other gemstones not in that category are considered semi-precious. The most popular of these are agate , rose quartz , black onyx , and the 12 birthstones . There are other ways to classify different gemstones, such as natural, synthetic, and imitation gemstones. Organic and non-organic designations are sometimes used for formations such as fossilized tree resin, better known as amber.

What are some popular gemstone cuts?

Gemstone cuts affect the overall appearance of the gemstone and give it a unique shape. Some cuts have many facets to reflect lots of light, whereas others let the natural color steal the show. Here are a few of the most popular cuts. Round-cut gemstones : Popular for engagement rings, these appear round from a top-down view, with lots of facets for a sparkly, brilliant ring. For an angular alternative, try an octagon cut. Marquise-cut gemstones : Instantly recognized for their elongated shape, marquise cuts are elliptical with two pointed ends, which can make your finger appear longer and slimmer. Trillion-cut gemstones : Also known as a trilliant cut, trillions are triangular shapes with curved or non-curved sides and many variations. Oval-cut gemstones : Like an elongated round cut, these excel at showing off brilliant, fiery gemstones such as diamonds and moissanite. Pear-cut gemstones : Sometimes referred to as teardrop or pendeloque cut, these blend the top pointed part of a marquise with the circular bottom of a round cut. Emerald-cut gemstones : Not just for emeralds, the emerald cut is rectangular with the corners cut off. Their signature look is complete with chiseled step cuts along the sides for a commanding appearance. Princess-cut gemstones : Square princess cuts maximize brilliance with stunning patterns in a timeless design. Princess cuts are popular for engagement rings and frequently include decorative pavé gemstones. Cushion-cut gemstones : These stunners are also square but have rounded corners for a smoother, romantic feel. Cabochon-cut gemstones : Rather than faceted, cabochon cuts are polished and shaped. Jewelers most often use them with opaque gemstones such as opal and jade.

What are the 12 birthday gemstones?

Rooted mostly in astrology and the zodiac, each birthday month is associated with a traditional and a modern gemstone. Both modern and traditional birthstones have their own meanings . January: Garnet for both modern and traditional February: Amethyst for both modern and traditional March: Traditionally bloodstone and aquamarine for modern April: Diamond for both modern and traditional May: Emerald for both modern and traditional June: Traditionally pearl and alexandrite for modern. July: Ruby for both modern and traditional August: Traditionally sardonyx and either peridot or spinel for modern September: Sapphire for both modern and traditional October: Traditionally opal and tourmaline for modern November: Traditionally topaz and citrine for modern December: Traditionally turquoise or lapis lazuli and zircon, blue topaz, or tanzanite for modern

What are some of the rarest gemstones?

Although there are many rare gemstones—such as diamonds, emeralds, sapphires, and rubies—a few are especially uncommon. These include tanzanite, black opal, red beryl, and alexandrite. Tanzanite and alexandrite are beloved for the way they change color in the light: Tanzanite changes between blue, violet, and burgundy; alexandrite turns green in the light and red in the dark. Opal gemstones by nature are rare, but the black version appears as a cosmic midnight sky found almost exclusively near Australia. Red beryl is a brilliant scarlet born out of specific environmental conditions.

How are gemstones graded?

Gemstones are graded according to rarity using the four Cs: color, clarity, cut, and carat. The higher grades fetch higher prices because they are considered rarer overall—but grades are used more as guidelines for choosing gemstones rather than head-to-head rankings. To better understand grading: Color refers to the gemstone's hue, tone, and saturation, with bold, rich colors often earning higher grades. There are some exceptions, like diamonds and other clear gemstones, which are prized for being nearly colorless. Whether you’re choosing gemstones for jewelry making or finely crafted jewelry , consider what color works best for your skin tone and use color as a guide. Lower-rated gemstone colors like pink rubies and baby-blue sapphires might turn more heads than the rarer, pure red or blue versions. Clarity refers to the number of inclusions in the gemstone, with fewer inclusions receiving higher grades. Inclusions are anything from hollow areas or fractures to other mineral imperfections that affect how light passes through the gemstone. Gems rated high in clarity are likely to have few to no fractures, meaning they are strong and well-suited for rings. Cut combines quality artistry and symmetry, significantly affecting the gemstone's brilliance and fire. Brilliance refers to how much white light is reflected; fire is the reflected colored light. Together, they create pattern and sparkle, which is known as scintillation. Each cut surface is called a facet, which should be smooth and mirror-like. More facets mean many tiny sparkles; fewer facets create more prominent flashes. Carat measures the weight of the gemstone. Weight is not equal across all gemstones because densities vary from stone to stone. For example, rubies are denser than diamonds, so a one-carat diamond looks larger than a one-carat ruby.

Gemstones

(1,455,305 Results)

MYSTIC TOPAZ Loose Gemstone 40To60Ct High Quality Rainbow Mystic Topaz Gemstone Pendant Size Faceted Mystic Topaz Jewelry Making

(458)

Sale Price $31.50
Original Price $105.00 (70% off)

From shop PricelessGemsHub

FREE shipping
Extremely Rare Large 5 Pc Opal Rough Lot 50 Cts AAA Grade Natural Ethiopian Opal Raw Suitable For Cut And Jewelry Fire Opal Crystal Gemstone

(279)

Sale Price $48.00
Original Price $160.00 (70% off)

From shop InfinityOpal

FREE shipping
Flawless 14.30 Ct Natural Royal DARK Blue Tanzanite Cushion Cut Loose Gemstone GIT Certified Precious BOMB Fire And Heart Touching Gemstone

(84)

Sale Price $30.00
Original Price $119.99 (75% off)

From shop nooreilahigems

FREE shipping
Bulk Semi precious Faceted Gemstones Wholesale Lot, Mixed Loose Gemstones, Assorted Shape-Size-Weight, Hydro Quartz Multi Gemstones, 6-16mm

(667)

Star Seller

Sale Price $34.40
Original Price $43.00 (20% off)

From shop Gemstonesplace
5Pcs Natural Oyster Copper Turquoise Pear Shape Cabochon lot - Oyster Turquoise Cabochon - Loose Oyster Turquoise Gemstone 10x14mm cabochon

(138)

Sale Price $14.98
Original Price $49.92 (70% off)

From shop MIXGEMSTONEUSA

FREE shipping
AAA+++ Top Quality Natural Ethiopian Opal Cabochon Lot Welo Opal Making Jewelry

(3,116)

Sale Price $12.60
Original Price $42.00 (70% off)

From shop KareemGemsWorld

FREE shipping
50 Pcs Natural Flawless Mogok Red Ruby Round Cut Loose Gemstone Certified-Wholesale Loose Gem-AAA+ Top Quality Ruby-Ring & Jewelry Making

(153)

Sale Price $25.00
Original Price $100.00 (75% off)

From shop CutsAndRough

FREE shipping
AAA+++Natural Mix Cabochon, Mix Lot, Cabochon Loose Gemstone, Wholesale Lot Gemstone Cabochon, Mix Shape Mix Size Wholesale Lot Loose Stone.

(3,116)

Sale Price $12.90
Original Price $43.00 (70% off)

From shop KareemGemsWorld

FREE shipping
Over 200 Carats of Loose Natural Gemstone Mix Parcel Lot

(11,771)

$49.99

From shop pinnaclediamonds

FREE shipping

Bestseller
Natural Colombia Green Emerald 11 Ct Loose Gemstone For Ring Use Or Wedding Purpose Emerald Cut Loose Gemstone, valentine Day gift

(673)

Sale Price $26.99
Original Price $44.99 (40% off)

From shop GEMSNUT

FREE shipping
Ethiopian fire Opal Mix lot fire opal Cabochon top quality opal gemstone AAA Natural multi fire Opal cabochon for jewelry making use.

(1,559)

Sale Price $11.40
Original Price $37.99 (70% off)

From shop DSKgemsSTUDIO

FREE shipping
Rare Natural AAA+ Flawless Mozambique Pigeon Blood Red Ruby Round Cut Loose Gemstone Certified-Ring & Jewelry Making-AAA Top Quality Ruby

(153)

Sale Price $20.00
Original Price $80.00 (75% off)

From shop CutsAndRough

FREE shipping
One Time Sale Ruby Rough Natural 100 -1000 Ct Certified Natural Uncut Earth Mined 77mmx47mm African Pigeon Blood Red Ruby Big Rough Gemstone

(257)

Sale Price $15.31
Original Price $61.23 (75% off)

From shop gemstells

FREE shipping
Rare Natural Royal Blue Ceylon Sapphire Emerald Cut Loose Gemstone GIT Certified/AAA+ Top Quality Gemstone/Ring & Jewelry Making Gemstone

(153)

Sale Price $20.00
Original Price $80.00 (75% off)

From shop CutsAndRough

FREE shipping
AAA+++ Top Quality Natural Ethiopian Black Opal Cabochon Lot Welo Opal Making Jewelry

(3,116)

Sale Price $12.60
Original Price $41.99 (70% off)

From shop KareemGemsWorld

FREE shipping
Flawless 9.85 Ct Natural Gray-Purple Musgravite Cushion Cut Loose Gemstone GIT Certified Very Rare Musgravite BOMB Fire LusterAnd Precious

(84)

Sale Price $28.08
Original Price $112.32 (75% off)

From shop nooreilahigems

FREE shipping
Opal Rough AAA Grade Large Size Ethiopian Welo Opal Raw Suitable For Cutting And Making Jewelry Dry Opal Rough Lot Fire Opal Crystal

(279)

Sale Price $15.00
Original Price $50.00 (70% off)

From shop InfinityOpal

FREE shipping
Best Quality 100% Natural White Scolecite Round Shape Smooth Beads Making For Jewelry 16 Inch Strand Beads Natural Stone Natural Beads

(47)

Sale Price $43.01
Original Price $86.02 (50% off)

From shop Beadsgemsshop

FREE shipping
Over 100 Carats of Loose Natural Semiprecious Gemstones

(11,771)

$29.99

From shop pinnaclediamonds

Bestseller
OPAL Raw Crystals - AA Grade, Large - Bulk Raw Opal, Rough Opal Lot, Welo Opal, E0216

(82,936)

Star Seller

Sale Price $40.00
Original Price $100.00 (60% off)

From shop ThrowinStones

FREE shipping
Super Quality Opal Rough Large Size AAA Grade Ethiopian Welo Opal Raw Suitable For Cutting And Jewelry Dry Opal Rough Lot Fire Opal Crystal

(279)

Sale Price $17.10
Original Price $57.00 (70% off)

From shop InfinityOpal

FREE shipping
Top Quality Ceylon Blue Sapphire 20.00 Ct Certified Cushion Cut Loose Gemstone From SRI LANKA

(8)

Star Seller

Sale Price $71.50
Original Price $110.00 (35% off)

From shop HEBAGEMSTORE

FREE shipping
Uncut Raw Tanzanite 100-1000 Ct Blue Tanzanite Raw Rough Natural Uncut Healing Earth Mined Tanzanite Loose Gemstone Raw Stone Free Shipping

(257)

Sale Price $17.48
Original Price $69.91 (75% off)

From shop gemstells

FREE shipping
Tanzanite Wholesale Lot, Natural Tanzanite Gemstone, Tanzanite Faceted Gemstone, Tanzanite Cut Stone, Loose Gemstone, December Birthstone,

(3,116)

Sale Price $11.70
Original Price $38.99 (70% off)

From shop KareemGemsWorld

FREE shipping
2 MM Natural Green Emerald Round Normal Cut Loose Gemstone Lot , Natural gemstones

(996)

$38.00

From shop Suttikarngems

FREE shipping
Natural Tanzanite 0.82 cts Oval Cut Gemstone for ring jewelry in reasonable price Sky blue Tanzanite stone from Tanzania

(8)

$82.00

From shop MehniyaJewelry

FREE shipping
0.80mm to 4.00mm Full White D Color Small Round Brilliant Diamond Cut Loose Moissanite For Ring, Earring, Jewellery Making (Wholesale Price)

(504)

Star Seller

Sale Price $32.00
Original Price $80.00 (60% off)

From shop Jewenty

FREE shipping
7 Ct Certified Extremely Rare AAA+ Natural Grandidierite Greenish Montana Round Shape Beautiful Cut Loose Grandidierite Gemstone For Jewelry

(111)

Sale Price $28.67
Original Price $47.79 (40% off)

From shop Gemsmart1

FREE shipping
1012 Gram Unique Blue & Gray Phantom FLUORITE With CALCITE Crystal Specimen From Pakistan @... Size : 133x80x56 mm

(432)

Sale Price $149.25
Original Price $199.00 (25% off)

From shop SunriseMinerals
Wonderful Quality Labradorite Oval Shape Cabochon Loose Gemstone Size- 6x8 MM. - 20x30 MM. Beautiful Blue Fire Labradorite For Jewelry.!!

(1,055)

Sale Price $3.69
Original Price $14.78 (75% off)

From shop IshraGemsStore

FREE shipping
Natural Opal bracelet, Amethyst Bracelet with opal, February Birthstone, October Birthstone, Genuine Gemstone Dainty Beaded Bracelet

(260)

Sale Price $8.08
Original Price $16.15 (50% off)

From shop RealCrystalGemstoneS
Natural Rainbow Moonstone Flat Back Cabochon Loose Gemstone

(2,016)

Sale Price $4.98
Original Price $16.60 (70% off)

From shop gemsocean
8.10 Carat AAA+ Natural Purple Tanzanite Round Cut Extremely Rare Loose Gem| Halloween Gift | Free Delivery

(673)

Sale Price $26.72
Original Price $44.54 (40% off)

From shop GEMSNUT

FREE shipping
Natural Crystal Watermelon Tourmaline Gemstone Faceted Doublet Bi Color Tourmaline Doublet Octagon 10x14mm Emerald cut stone Loose Gemstone

(810)

Star Seller

$26.99

From shop Lovewishjewels

FREE shipping

Bestseller
11.70 CTS Special Cut Exceptional Piece Of Dark Blue Goshonite/Beryl

(31)

Sale Price $525.00
Original Price $700.00 (25% off)

From shop Etsygemgallery
2.5mm Rounds Rainbow Sapphires Tennis Bracelet loose stones sets Beautiful Desing

(388)

Star Seller

Sale Price $163.01
Original Price $217.35 (25% off)

From shop Zehragems

FREE shipping
2.7 - 2.8 MM Natural Multi Color Sapphire Round Diamond Cut Loose Gemstones Lot

(996)

$35.00

From shop Suttikarngems

FREE shipping

Only 3 left — order soon
Raw Emerald Crystal, Natural Green Emerald Rough, A Grade Emerald Crystal Hexagon Shape Emerald Rough, Emerald Birthstone Gift For Your Love

(28)

Sale Price $11.85
Original Price $39.50 (70% off)

From shop AfgemsIndia

FREE shipping
Brazilian Paraiba Tourmalines Loose Gems for Custom Jewelry Design (Sold Individually)

(256)

Star Seller

$185.00

From shop HiddenTreasureGems

FREE shipping
GFCO Certified Natural 1.75Ct Blue Spinel gemstone, Heart cut, Tanzania

(575)

Star Seller

$412.81

From shop GRALJEWELRY

FREE shipping
Natural Pietersite Pair Cabochon Peitersite Pair Gemstone Loose Gemstone Both Side Polished Smooth Pietersite, Genuine Pietersite Stone

(460)

Star Seller

Sale Price $11.97
Original Price $39.90 (70% off)

From shop Cabochonsellers
Natural Unheated Tanzanite, Rare Peacock Colour , 1.35 Ct Weight , 7.76 × 5.59 × 4.28 MM Size , Loupe Clean , Loud peacock Colour

(955)

Star Seller

$202.00

From shop TanzaniteGems

FREE shipping

Only 1 left — order soon
Natural Hemimorphite Cabochon Loose Gemstone Pear Shape Hemimorphite Gemstone Oval Shape Hemimorphite Cabs ( Hemimorphite As Picture

(644)

Star Seller

Sale Price $7.96
Original Price $28.44 (72% off)

From shop A2ZCabochon
Natural Rainbow moon stone 8 Pieces moon, Crescent Moon jewelry, Carving gemstone moon, Top drilled moon for jewelry, moon size 7x18 mm moon

(3,248)

Star Seller

Sale Price $22.00
Original Price $55.00 (60% off)

From shop RareStoneBeads

FREE shipping
Tricolour Tourmaline Pair

(40)

Sale Price $913.75
Original Price $1,075.00 (15% off)

From shop Lagoongemsco
High Luminescence LUAG Lutetium Aluminum Garnet Gems Synthetic Laser Crystal Fluorescent Lab Stone Synthesis of Loose Gemstones

(141)

Star Seller

$17.00

From shop FairytreasuryStore

Bestseller
Multi Tourmaline Crystal | Tourmaline Minerals | Multi Tourmaline Sticks, Watermelon Tourmaline Beads, Tourmaline Drilled Crystals **6-10 MM

(1,889)

Sale Price $21.00
Original Price $30.00 (30% off)

From shop watermelongallery
Natural Tanzanite , AAA+ Colour Trillion Shape , 0.25 Ct Weight , 4.10 × 4.07 MM Size , Loupe Clean

(955)

Star Seller

$89.00

From shop TanzaniteGems

FREE shipping

Only 1 left — order soon

There's so much more for you to discover

Review spotlight

Here is a selection of four-star and five-star reviews from customers who were delighted with the products they found in this category.

Gemstones

MYSTIC TOPAZ Loose Gemstone 40To60Ct High Quality Rainbow Mystic Topaz Gemstone Pendant Size Faceted Mystic Topaz Jewelry Making

Extremely Rare Large 5 Pc Opal Rough Lot 50 Cts AAA Grade Natural Ethiopian Opal Raw Suitable For Cut And Jewelry Fire Opal Crystal Gemstone

Flawless 14.30 Ct Natural Royal DARK Blue Tanzanite Cushion Cut Loose Gemstone GIT Certified Precious BOMB Fire And Heart Touching Gemstone

Bulk Semi precious Faceted Gemstones Wholesale Lot, Mixed Loose Gemstones, Assorted Shape-Size-Weight, Hydro Quartz Multi Gemstones, 6-16mm

5Pcs Natural Oyster Copper Turquoise Pear Shape Cabochon lot - Oyster Turquoise Cabochon - Loose Oyster Turquoise Gemstone 10x14mm cabochon

AAA+++ Top Quality Natural Ethiopian Opal Cabochon Lot Welo Opal Making Jewelry

50 Pcs Natural Flawless Mogok Red Ruby Round Cut Loose Gemstone Certified-Wholesale Loose Gem-AAA+ Top Quality Ruby-Ring & Jewelry Making

AAA+++Natural Mix Cabochon, Mix Lot, Cabochon Loose Gemstone, Wholesale Lot Gemstone Cabochon, Mix Shape Mix Size Wholesale Lot Loose Stone.

Over 200 Carats of Loose Natural Gemstone Mix Parcel Lot

Natural Colombia Green Emerald 11 Ct Loose Gemstone For Ring Use Or Wedding Purpose Emerald Cut Loose Gemstone, valentine Day gift

Ethiopian fire Opal Mix lot fire opal Cabochon top quality opal gemstone AAA Natural multi fire Opal cabochon for jewelry making use.

Rare Natural AAA+ Flawless Mozambique Pigeon Blood Red Ruby Round Cut Loose Gemstone Certified-Ring & Jewelry Making-AAA Top Quality Ruby

One Time Sale Ruby Rough Natural 100 -1000 Ct Certified Natural Uncut Earth Mined 77mmx47mm African Pigeon Blood Red Ruby Big Rough Gemstone

Rare Natural Royal Blue Ceylon Sapphire Emerald Cut Loose Gemstone GIT Certified/AAA+ Top Quality Gemstone/Ring & Jewelry Making Gemstone

AAA+++ Top Quality Natural Ethiopian Black Opal Cabochon Lot Welo Opal Making Jewelry

Flawless 9.85 Ct Natural Gray-Purple Musgravite Cushion Cut Loose Gemstone GIT Certified Very Rare Musgravite BOMB Fire LusterAnd Precious

Opal Rough AAA Grade Large Size Ethiopian Welo Opal Raw Suitable For Cutting And Making Jewelry Dry Opal Rough Lot Fire Opal Crystal

Best Quality 100% Natural White Scolecite Round Shape Smooth Beads Making For Jewelry 16 Inch Strand Beads Natural Stone Natural Beads

Over 100 Carats of Loose Natural Semiprecious Gemstones

OPAL Raw Crystals - AA Grade, Large - Bulk Raw Opal, Rough Opal Lot, Welo Opal, E0216

Super Quality Opal Rough Large Size AAA Grade Ethiopian Welo Opal Raw Suitable For Cutting And Jewelry Dry Opal Rough Lot Fire Opal Crystal

Top Quality Ceylon Blue Sapphire 20.00 Ct Certified Cushion Cut Loose Gemstone From SRI LANKA

Uncut Raw Tanzanite 100-1000 Ct Blue Tanzanite Raw Rough Natural Uncut Healing Earth Mined Tanzanite Loose Gemstone Raw Stone Free Shipping

Tanzanite Wholesale Lot, Natural Tanzanite Gemstone, Tanzanite Faceted Gemstone, Tanzanite Cut Stone, Loose Gemstone, December Birthstone,

2 MM Natural Green Emerald Round Normal Cut Loose Gemstone Lot , Natural gemstones

Natural Tanzanite 0.82 cts Oval Cut Gemstone for ring jewelry in reasonable price Sky blue Tanzanite stone from Tanzania

0.80mm to 4.00mm Full White D Color Small Round Brilliant Diamond Cut Loose Moissanite For Ring, Earring, Jewellery Making (Wholesale Price)

7 Ct Certified Extremely Rare AAA+ Natural Grandidierite Greenish Montana Round Shape Beautiful Cut Loose Grandidierite Gemstone For Jewelry

1012 Gram Unique Blue & Gray Phantom FLUORITE With CALCITE Crystal Specimen From Pakistan @... Size : 133x80x56 mm

Wonderful Quality Labradorite Oval Shape Cabochon Loose Gemstone Size- 6x8 MM. - 20x30 MM. Beautiful Blue Fire Labradorite For Jewelry.!!

Natural Opal bracelet, Amethyst Bracelet with opal, February Birthstone, October Birthstone, Genuine Gemstone Dainty Beaded Bracelet

Natural Rainbow Moonstone Flat Back Cabochon Loose Gemstone

8.10 Carat AAA+ Natural Purple Tanzanite Round Cut Extremely Rare Loose Gem| Halloween Gift | Free Delivery

Natural Crystal Watermelon Tourmaline Gemstone Faceted Doublet Bi Color Tourmaline Doublet Octagon 10x14mm Emerald cut stone Loose Gemstone

11.70 CTS Special Cut Exceptional Piece Of Dark Blue Goshonite/Beryl

2.5mm Rounds Rainbow Sapphires Tennis Bracelet loose stones sets Beautiful Desing

2.7 - 2.8 MM Natural Multi Color Sapphire Round Diamond Cut Loose Gemstones Lot

Raw Emerald Crystal, Natural Green Emerald Rough, A Grade Emerald Crystal Hexagon Shape Emerald Rough, Emerald Birthstone Gift For Your Love

Brazilian Paraiba Tourmalines Loose Gems for Custom Jewelry Design (Sold Individually)

GFCO Certified Natural 1.75Ct Blue Spinel gemstone, Heart cut, Tanzania

Natural Pietersite Pair Cabochon Peitersite Pair Gemstone Loose Gemstone Both Side Polished Smooth Pietersite, Genuine Pietersite Stone

Natural Unheated Tanzanite, Rare Peacock Colour , 1.35 Ct Weight , 7.76 × 5.59 × 4.28 MM Size , Loupe Clean , Loud peacock Colour

Natural Hemimorphite Cabochon Loose Gemstone Pear Shape Hemimorphite Gemstone Oval Shape Hemimorphite Cabs ( Hemimorphite As Picture

Natural Rainbow moon stone 8 Pieces moon, Crescent Moon jewelry, Carving gemstone moon, Top drilled moon for jewelry, moon size 7x18 mm moon

Tricolour Tourmaline Pair

High Luminescence LUAG Lutetium Aluminum Garnet Gems Synthetic Laser Crystal Fluorescent Lab Stone Synthesis of Loose Gemstones

Multi Tourmaline Crystal | Tourmaline Minerals | Multi Tourmaline Sticks, Watermelon Tourmaline Beads, Tourmaline Drilled Crystals **6-10 MM

Natural Tanzanite , AAA+ Colour Trillion Shape , 0.25 Ct Weight , 4.10 × 4.07 MM Size , Loupe Clean

There's so much more for you to discover

Related to Gemstones