Price of Avalon Eidolon Diamonds

I think Daniel gives an accurate assessment. I bought a pair from a dealer in pristine condition for $19k, and felt that I had paid a bit higher than I should.

The last pair listed here in premium finish were priced at $16.5K. They were from a private seller, I believe.
They sold (or the lsiting was pulled), in a few days.
The last 2 pair listed by dealers were listed for $21K, and took longer to sell.

How much are you willing to accept for them? That's the question you should be asking yourself.

Bingo. That is clearly one of the main criteria, however, you do have to anchor your expectations to current market prices somewhat, so subscribing to the Agon Bluebook service is certainly one way of doing that, although the caveat there is that the Bluebook data seems a little bit old and outdated, so that is not a great barometer of where more recent transactions have cleared. Triangulate between the minimum price you are willing to accept, bluebook data, and current Agon listings to see where you should settle out. Good luck.

How much are you willing to accept for them? That's the question you should be asking yourself.

You may have to pay for that info using the Audiogon Blue Book Index which you can subscribe to. Otherwise you can take a usual percentage of original list price. I was always of the opinion that an average used price should be % 50 of new. If really mint and almost not used 60-70% of original price. You also have to take into account "street price" if original price is very often discounted.