So you will not stray on the wrong or mistaken path:
Antique makes a little difference in value of the jewels. Also, if you look in the Traders Forum, 99% of the jewels that sell for up to 20M to 1p sometimes are antique. So antique does not necessarily make the item bad. Agree they wear out but slowly.
What makes them or breaks them is the mods on them, and whether buyers/players need them or not, and how badly they need the mods. I reckon..