The seller agreed on a price and ended the auction. To be honest, it doesn't matter if it's worth 1m - 5m - or even 1 billion gold, it's all a matter of what the seller is willing to let it go for and what the buyer is willing to pay for it. The market is so wishy, washy today it's not even funny.
Lynk says you undersold it by a long shot, but I don't really see how? Crystalline ring offers 20 SDI and way more mods, especially if you used the faction ring for FCR 3. 18 SDI is max on Shame/Covetous loot, so it's close to max and max on the Mana Increase, cool. Nothing to special, but definitely better than the average jewel.
Anyhow, auction closed-lets move on.