Fine jewelry posts have long been made within a consistent gauge range, which is why clutch back replacement is rarely complicated. All you have to do is pick a metal color and if you want the standard or comfort fit.
Built For Ease
The post's diameter follows an industry standard that ensures consistent fit across backs from different manufacturers. In practice, this means the spring wings or threaded bore of a replacement back will engage the post correctly without modification, regardless of whether the back came from the same maker as the earring.
Stone Story
Cubic zirconia was developed in a Soviet laboratory in the 1970s as a synthetic alternative to diamond, produced by stabilizing zirconium oxide into a cubic crystalline structure. The material was commercially adopted for jewelry almost immediately because it solved the specific problem of replicating diamond's optical character at a cost that made wide production practical.