Hi thanks for your question. From your photo the style of this looks relatively modern.
In 1906 the metals act was passed. Before that year there were many misleading marks. Although its very unlikely to be earlier than this date, have you tested the metal content yourself? Have you tested the diamonds? Are you sure they are the real thing and not moissanite diamonds?
14 K gold or 585 (parts per 1000) or 58.5% gold is a common gold mark in the USA. We can't see the crown mark so unable to comment on maker's mark. You are welcome to attach another photo of the crown mark in a follow-up submission.
