The Diamond Galleries made a pretty faithful reproduction in 1996 that can still be found on eBay occasionally (where I bought mine) and IS an accurate reproduction EXCEPT for the following-
Gold finish instead of silver
Adjustable ring band
Stamped "repro" and "1995 Argosy" on the inside.
It comes in a red velvet ring box with a COA.
In case you are interested, Baen books created it's own ring for "The Spider" as part a promotional package for the reprints that lasted two volumes. It was given away at conventions and not sold. It has a much larger face than the original and a silver finish but the ring itself is only a thin band. It IS very well made.