3 5/8 ct Ruby Stud Earrings By Kari - February 5, 2016 530 Use $30 off coupon code: SALE and get free shipping. Ruby studs are a jewelry classic and this pair is the perfect example. Cushion-cut created rubies totaling 3 5/8 ct are set in 14K gold. Pieces measure 1/4 by 1/4 inches.