Blue gold stone glittery Artisan Necklace India Vintage sandstone

There is a marking on the back but I can’t make out what it is , it could be in a foreign language, I thought it was a Sterling Silver Mark but unsure, there are two types of goldstone this is the dark one, looks black to me but I believe it is called blue, this one is very glittery , a classic Setting From India. Called the stone Of ambition, gold stone is thought to assist in attaining goals. Some consider it to be a symbol of ambition and drive, believed to reduce tension, revitalize the wearer and encourage a positive attitude