These are one of my favorite gemstones. Black Spinel. It is very hard and durable stone. It is a 8 on the hardness scale that is why you have the luster. It is a natural color. The only stones harder are the Corundums and Diamonds. These 2 gemstones have excellent facets and are 10mm in size. I have added Thai Hill Tribe silver handmade bead caps. They sparkle in the light and are for everyday wear. They go with everything. 10mm faceted Black Spinel gemstones, natural color Hill Tribe silver bead caps Fishhook ear wire Dangle 1 -1/4 inches.