Sterling Silver London Blue Topaz 7 mm Round Stud Earrings Transport yourself to a sunny beach with these tranquil sea blue studs featuring 3cctw 7mm round natural London blue topaz gemstones. Prongs set in 1g 925 sterling silver with friction post backing, these studs are indeed the best gift for valentine's day, birthday, engagement, wedding, anniversary and other occasions. Imported All our diamond suppliers confirm that they comply with the Kimberley Process to ensure that their diamonds are conflict free.