Lemon topaz gemstone 925 sterling silver ring. Gemstone:Topaz, material:Silver, length:10mm, width:12mm, weight:5.7grm, colour:Yellow. How to get ring size? Measurements: - cut a thin strip of paper. Wrap the paper around your finger. Make sure the paper is below the joint of your finger and close to your knuckle. Mark the spot where the paper meets and measure the distance with your ruler. Use the following chart to determine your ring size. Inside diameter in mm ( size ) :- 14mm(3), 15mm(4), 15.6mm(5), 16.6mm(6), 17.2mm(7), 18.1mm(8), 19.1mm(9), 19.7mm(10), 20.7mm(11), 21.6mm(12), 22.3mm(13), 23.2mm(14), >23.6mm(15) .5mm+/-.