Beryl: Beryllium aluminum cyclosilicate. Be₃Al₂(SiO₃)₆  is the basic chemical formula for this mineral that, with the proper impurities, produces Emerald and Aquamarine. 

Carat: The measurement by which gemstones are weighed. Every variety of gemstone, carat-for-carat, will be of a different size. For example, a two-carat amethyst would be much smaller than a two-carat diamond.

Corundum: This mineral family of crystalline aluminum oxide (Al₂O₃) is mother to Sapphire and Ruby. 

Electroplate: A process by which a thin layer (usually about 2 microns) of precious metal is electrochemically bonded to a base metal. Not featured at Arelles.com.

Goldtone/Silvertone: A thinner version of electroplate, at approximately .175 microns, also not offered at Arelles.com.

Karat: Measures the amount of gold in an alloy. Pure gold is expressed as 24K, therefore 10K gold as an example would be 10/24, or 5/12 (58.3%)  pure gold. The remainder is copper and nickel.

Olivine: Another very common mineral, this is a magnesium iron silicate with the chemical formula (Mg,Fe)₂SiO₄. Peridot is the gem-grade variety of this mineral.

Quartz: Chemically known as silicon dioxide (SiO₂), quartz is the second most common mineral in the earth's crust. However, with the presence of the proper impurities, quartz brings us the gemstones Amethyst and Citrine.

Sterling Silver: An alloy containing 92.5% silver, and 7.5% copper.

Total Carat Weight (TCW, ct. t.w.): Refers to the total weight of diamonds in a multiple-stone setting.

Vermeil: Gold over sterling silver, with a coating 50 times thicker than electroplate.