Diamond is the hardest known mineral on Earth. Its name means “hardest” in Arabic. Its main constituent is carbon, and may sometimes contain trace amounts of silicon, aluminum, calcium, magnesium, iron, nitrogen or boron. Diamond belongs to the isometric crystal family, and its crystal habit is octahedral. Diamonds of high purity is colorless and transparent, although some with trace amounts of impurities may produce colored diamonds, such as blue (boron), yellow (nitrogen), and pink (manganese).

Because diamonds have high refractive indices, a specimen that is cut proportionally will exhibit total internal reflection and produces brilliant specks of lights, referred to as “fire.” A perfectly cut diamond with 58 facets will produce shadow patterns shaped like arrows and hearts. This type of cut is known as “Hearts and Arrows”, also known as “Cupit” cut.

Sometimes diamonds may include small materials of various types. Some of the common inclusions are pyropes, enstatites, spinels, graphites or small diamonds. The amount of inclusions in a diamond determines its degree of clarity.