Durability is part of the appeal of Green Topaz, not merely a technical footnote. Jewellers who need dependable wear resistance often come to it for different reasons, but identification still comes back to green body colour, 8 Mohs hardness, and vitreous lustre.

Green Tourmaline is often discussed with one eye on colour and the other on where the material comes from. That combination of green body colour, 7 Mohs hardness, and vitreous lustre is what usually makes it recognisable in practice.

Grey chalcedony is a neutral-toned chalcedony variety used in cabochons, beads, and carvings.

Grossular is a calcium-aluminum garnet species including tsavorite and hessonite varieties.

Harlequin opal is a trade pattern descriptor for precious opal with geometric, patchy color play.

Harlequin quartz is a trade name used for quartz with vivid internal red/orange inclusion patterning.

Hawk's eye is a blue-grey chatoyant quartz variety formed by silicification of fibrous host textures.

Locality plays an important role in how Heliodor is understood in the gem trade. Collectors and lapidaries comparing similar stones often come to it for different reasons, but identification still comes back to blue body colour, 7.5 Mohs hardness, and vitreous lustre. The secondary green note often matters more than people expect when separating it from lookalikes.

Hematite is an iron oxide mineral identified in gem use by metallic lustre and red-brown streak.

Hessonite is the orange to brownish-orange variety of grossular garnet.

Hiddenite is the green gem variety of spodumene, valued for bright yellow-green tones.

Honey calcite is a yellow variety of calcite used for ornamental stones and carvings.

Hydro quartz refers to hydrothermally grown synthetic quartz used as a gem and decorative material.

Ice quartz is a trade name for quartz with frosted or crackled internal appearance.

Iceland spar is a transparent variety of calcite noted for pronounced birefringence and double refraction.

Imperial jade is the highest-value trade grade of vivid green jadeite, distinguished by color quality and translucency.

Durability is part of the appeal of Imperial Topaz, not merely a technical footnote. Jewellers who need dependable wear resistance often come to it for different reasons, but identification still comes back to blue body colour, 8 Mohs hardness, and vitreous lustre. The secondary yellow note often matters more than people expect when separating it from lookalikes.

Part of the identity of Indicolite comes from the producing regions associated with it. That combination of green body colour, 7 Mohs hardness, and vitreous lustre is what usually makes it recognisable in practice. The secondary pink note often matters more than people expect when separating it from lookalikes.

Iolite is the gem variety of cordierite, known for pronounced pleochroism from blue-violet to pale yellow-grey.

Jade is valued as much for texture and toughness as for colour. A fine piece has a compact, almost glowing appearance that feels different from ordinary green ornamental stone, which is one reason jade has held cultural importance for so many centuries.

Part of the identity of Jadeite comes from the producing regions associated with it. That combination of green body colour, 6.5 Mohs hardness, and silky lustre is what usually makes it recognisable in practice. The secondary white note often matters more than people expect when separating it from lookalikes.

Jasper is an opaque microcrystalline quartz aggregate with diverse colors and patterns.

Kambaba jasper is a trade-name ornamental rock with green-black orbicular patterns, not a strict jasper species term.

Kunzite profile is under factual gemological review. Properties shown here are provisional unless marked as verified.