Mineral (Organic Gemstone)

Smoky Quartz

Silicon dioxide with aluminum impurities (SiO2)

Red Garnet (Almandine-Pyrope series)

Garnet Group, Almandine (Fe3Al2(SiO4)3) or Pyrope (Mg3Al2(SiO4)3)

Banded Chert in Matrix

Microcrystalline Quartz (SiO2)

Diamond

Diamond (pure Carbon, C)

Quartz (Milky/Cloudy Variety)

Silicon Dioxide (SiO2)

Moonstone (Feldspar)

Orthoclase or Oligoclase (KAlSi3O8)

Banded Agate (with possible Chalcedony layers)

Silicon dioxide (SiO2)

Chert (specifically Jasper or Flint variant)

Cryptocrystalline Quartz (SiO2)

Yellow Aventurine

Silicon Dioxide (SiO2) with inclusion of Mica

Lepidolite

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Red Jasper

Jasper (Silicon Dioxide based crypto-crystalline Quartz with Iron inclusions)

Quartz (Milky or Cloudy Quartz)

Silicon Dioxide (SiO2)

Diamond

Carbon (C)

Almandine Garnet

Almandine (Fe3Al2Si3O12)

Amethyst

Silicon Dioxide (SiO2) with trivalent iron (Fe3+) impurities

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Banded Agate

Chalcedony (Silicon Dioxide, SiO2)

Grey Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

Larimar

Pectolite (a blue variety of Pectolite)

Amethyst

Silicon Dioxide (SiO2) with trace Iron impurities

Amethyst (Chevron or Banded Amethyst)

Silicon Dioxide (SiO2) with iron impurities

Amethyst

Amethyst (Silicon Dioxide - SiO2 with ferric iron impurities)

Yellow Jasper

Silicon Dioxide (SiO2) with goethite or iron oxide inclusions

Snowflake Obsidian

Volcanic Glass with Cristobalite inclusions

Banded Agate (specifically Carnelian Agate slice)

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Sunstone and Green Aventurine

Sunstone: (Ca,Na)[(Al,Si)2Si2O8] (Plagioclase Feldspar Group); Green Aventurine: SiO2 (Quartz)

Amber (and Citrine Quartz)

Succinite (Amber) and Silicon Dioxide (SiO2)

Obsidian (in jewelry setting)

Volcanic Glass (Amorphous Silica)

Specular Hematite with Quartz

Ferric oxide (Fe2O3) and Silicon dioxide (SiO2)

Granitic Pegmatite

Granite Pegmatite (typically containing Quartz SiO2, Feldspar KAlSi3O8, and Muscovite)

Ruby

Corundum (Al2O3 with Chromium traces)

Rose Quartz (likely carved)

Rose Quartz (SiO2)

Tiger's Eye

Tiger's Eye (a variety of Chalcedony, which is a microcrystalline quartz with fibrous inclusions of oxidized crocidolite)

Banded Chert

Chert (a microcrystalline variety of quartz, SiO2 with minor impurities)

Black Tourmaline (Schorl)

Schorl (Na(Fe^2+)3Al6(Si6O18)(BO3)3(OH)4)

Demantoid Garnet on Matrix

Demantoid (variety of Andradite Garnet) - Ca3(Fe3+)2(SiO4)3

Diamond (Princess Cut Gemstone)

Carbon (C)

Chert (variations include Flint/Jasper)

Chert (Silicon Dioxide, SiO2)

Blue Quartzite

Quartzite (primarily SiO2) with inclusions like Dumortierite or Magnesio-riebeckite

Jadeite and Mixed Gemstones (Ruby, Sapphire, Emerald)

Jadeite (NaAlSi2O6), Corundum (Al2O3), Beryl (Be3Al2(Si6O18))

Chert (Chalcedony/Agate variety)

Silicon Dioxide (SiO2)

Obsidian

Volcanic glass (primary composition: SiO2)