Others know better than I, but it looks like a freshwater "button" pearl. I love the color combo & design! Than one, either the tooth test or against another known real pearl. If you start buying thrift store gold or silver... there are fake marks...especially 925... so you want to get a silver & gold acid test kit. 14k & 18k with stone is the cheapest...18k will test silver 925 & turns bright blue. 14k tests 14k & 10k (that looks different & you will need to watch youtubes for that look.) I have several gold fake marks & a sackful of fake silver 925... I have a a number of button pearl earrings with silver posts & some with silver looking posts...but not 925.