This is a beautiful Herkimer Quartz Diamond Gemstone Necklace on a delicate gold filled chain.  This Herkimer "diamond" crystal has exceptional clarity. Handmade by a local artisan.  
 
Herkimer diamonds are not actually diamonds, but double-terminated quartz crystals discovered within in and around Herkimer County, New York and the Mohawk River Valley.  Double Terminated Quartz is a highly sought-after quartz crystal with two natural terminated points on each end. It is said to have metaphysical and physical properties far more powerful than other quartz crystals. These points allow for optimum energy flow through the stone so that you can get the most out of it.