We are dealing in artifacts from many diverse cultures that span vast periods of history.

The ancient period ended with the fall of the Roman Empire, around for 476 AD. It would be a safe assumption to refer to any artifact from that time period as ancient. The Islamic period ended around 1500 AD (a thousand years later). Would it be safer to refer to the artifacts from the Islamic period as Islamic or ancient? I use the word safer for a reason, a legal definitive reason and not a subjective euphemism for something really old.

The 18th - 20th century is listed as the modern period. With the history of beads dating back over 75,000 years, modern trade beads are from the modern period of bead history.

It's time to educate yourselves, learn to refer to age by its proper historical period. Then educate your customers to do the same. This is what the most reputable sellers do.