Lab Created Blue Star Sapphire Earrings Fascinating Brilliance! This stone is reminiscent of the vintage “Lindy” synthetic Star Sapphire of the 50s thru 70s. The star effect, known as an “asterism”, is more defined in a lab-grown Sapphire. They are identical in chemical composition, brilliance, and physical appearance as their natural counterpart, however they have fewer flaws, are not mined from the ground, and are much less expensive. They are an extremely durable stone with a Mohs scale hardness or 9 (a Diamond is 10) Stones are 8mm 4 Prong mounted in 925 Sterling Silver setting. 6mm is about the size of a large green pea (Please see reference photos). The posts are 3/8" long. Polishing cloth for all types jewelry included. Shipped in gift box. Please note that the star effect or "asterism" of a Star Sapphire, is not a fixed element. It is the result of direct light, artificial or natural. The brighter the light source, the brighter the star display. In low light or shaded settings the star will be less visible. All photos are taken with direct light. Two types of 925 Sterling backs are included for preference or just to have a backup pair (Rubber core bullet style and traditional friction catch).