The full name of this is actually Petite Hammered Disc Birthstone Pendant. Jennifer Alfano has a few different designs, with the stone for each month. As my upcoming birthday is in September, sapphire it is.

This particular piece is hammered 18k yellow gold, slightly domed, measuring 12 mm diameter/approx 1/2″), with a 6mm cabochon sapphire.These pieces are custom made and require a few weeks lead time. The date can also be engraved on the reverse; fortunately, I’m pretty good at remembering my birth date…..  Price ranges from USD $$1,185–$1,250 and the chain is not included (though Alfano sells them).