three genuine 4mm London blue gemstones are set in this handmade .999 fine silver bracelet. The foxtail chain is hand woven from 20 ga fine silver wire. The gemstone settings and hook and loop clasp is make of sterling silver. the bracelet is adjustable from about 6 1/2 to slightly over 7 1/2 inches comes with black velvet gift box Topaz is a very hard material - 8 on the Mohs hardness scale - and blue topaz is a very pretty stone that is available in a wide range of vivid hues with a striking vitreous luster. It is also a very affordable gem when compared to the price per carat of similar colored gemstones such as aquamarine. While topaz is very hard, it is not the most durable gemstone. That's because it has perfect cleavage, a property it shares with diamond. That means it can be chipped or split by a sharp blow, so it should be protected from hard knocks.