Anthropogenic (Man Made)

Sandstone

Arenite (SiO2 primarily)

Chalk

Carbonate rock (mainly CaCO3)

Diamond (in Jewelry)

Carbon (C)

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Sandstone

Arenite (SiO2 composition dominant)

Quartzite

Metamorphic Quartzite (SiO2)

Diamond

Native Carbon (C)

Chert (Flint)

Silicon Dioxide (SiO2)

Diamond

Carbon (C)

Sandstone

Arenite (composed primarily of SiO2)

Chalk

Micrite (primarily Calcium Carbonate or CaCO3)

Pearl

Organic gemstone (Calcium carbonate - CaCO3)

Chert (variations include Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Diamond

Carbon (C)

Diamond

Carbon (C)

Quartzite

Metamorphic Quartzite (SiO2)

Sandstone

Arenite (SiO2, often with CaCO3 or Fe2O3 cement)

Vesicular Rhyolite

Rhyolite (High-silica volcanic rock)

Diamond

Diamond (pure carbon C)

Red Quartzite

Quartzite (Metamorphosed Quartz Arenite)

Quartzite

Metamorphic Quartz Rock (SiO2)

Quartzite

Metamorphic Quartzite (SiO2)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Sandstone

Arenite

Quartzite

Metamorphic Quartzite (SiO2)

Quartzite

Metamorphic Quartzite (SiO2)

Quartzite

Metamorphic Quartzite (primarily SiO2)

Quartzite

Metamorphic Quartzite (primarily SiO2)

Sandstone (Quartzose)

Sandstone (SiO2 dominated)

Coal (Bituminous Coal)

Caustobiolith / Sedimentary Rock

Sandstone

Arenite (primarily SiO2)

Diamond

Carbon (C)

Sandstone

Clastic Sedimentary Rock

Diamond

Diamond (pure Carbon, C)

Quartzite

Metamorphic Quartzite

Chert (varietal: Flint/Jasper)

Silicon Dioxide (SiO2)

Fossilized Shell in Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Diamond (or Diamond Simulant)

Carbon (C) or Cubic Zirconia (ZrO2)

Basalt

Basalt

Diamond in Kimberlite

Diamond in Kimberlite Matrix (Diamond: C, Kimberlite: complex Potassic Peridotite)

Diamond (or Cubic Zirconia)

Carbon (C) or Zirconium Dioxide (ZrO2)