Organic Gemstone (Not A Mineral)

Grey Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

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

Larimar

Pectolite (a blue variety of Pectolite)

Obsidian (in jewelry setting)

Volcanic Glass (Amorphous Silica)

Snowflake Obsidian

Volcanic Glass with Cristobalite inclusions

Banded Agate (specifically Carnelian Agate slice)

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Amber (and Citrine Quartz)

Succinite (Amber) and Silicon Dioxide (SiO2)

Specular Hematite with Quartz

Ferric oxide (Fe2O3) and Silicon dioxide (SiO2)

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)

Sunstone and Green Aventurine

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

Granitic Pegmatite

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

Diamond (Princess Cut Gemstone)

Carbon (C)

Chert (variations include Flint/Jasper)

Chert (Silicon Dioxide, SiO2)

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

Chert (Chalcedony/Agate variety)

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))

Kunzite

Spodumene (LiAlSi2O6), variety Kunzite

Tree Agate

Silicon Dioxide (SiO2) with Chlorite/Manganese inclusions

Pegmatite

Pegmatitic Granite

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Quartz (Milky/Iron-stained)

Silicon Dioxide (SiO2)

White Chalcedony (Agate)

Silicon Dioxide (SiO2)

White Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chalcedony (Agate/Chert variety)

Silicon Dioxide (SiO2)

Beryl (Emerald Variety)

Beryllium aluminum silicate (Be3Al2Si6O18)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Granitic Pegmatite

Coarse-grained Granite (KAlSi3O8 + SiO2)

Jasper and Quartzite Pebble

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Biological Bone (Patella/Knee)

Patella (part of the Human Skeletal System)

Garnet (specifically Almandine)

Almandine (Fe3Al2(SiO4)3)