Ruby, Pink Sapphire + 10k Gold Infinity Stud EarringSome infinities are bigger than other infinities. The Fault in Our Stars And some, like this exceptional ruby + pink sapphire stud, are smaller. (But infinitely pretty, so there's that.) Cast from solid 10k yellow gold, this symbol of boundlessness is perfect for multiple piercings and for mixing and matching different earring charms. Some might say the possibilities are well, you know. Sold as a single. Solid 10k yellow gold stud; size: 4mm (0. 15")