This stone caught my eye while rummaging through a collection of pendant stones.  The agate pattern was enhanced manmade turquoise blue, not completely natural,  but isn't it stunning?  The turquoise magnesite beads, antiqued silver brass chain and silver pewter beads with toggle clasp make for an attractive 32 inch necklace.  Pictured above is what the "matching" earrings look like and may be purchased separately.  

Turquoise Colored Agate Necklace