Demantoids were very popular in the 1800's, but are rarely used today. A demiparure is a matching set of jewelry, usually containing a necklace, earrings, and a pin. See parure . The demi-parure above is a set by Trifari . A diadem is a tiara, a circular of semi-circular piece of jewelry worn on the head.
Diamonds are one of the hardest materials known.
Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419. Colors of diamonds range from colorless, yellow, orange, brown, to almost black. Canary diamonds have a deep yellow color. Dichroism is the property of having more than one color, especially when viewed from different angles. This effect can be artificially caused by a thin layer of a metallic oxides that is deposited on the surface of a material.