The stamina increase makes it more valuable, the only 5 SSI makes it less valuable.
An SSI 10 and HCI 15 costs 10M.
Since you can't imbue stamina on, I'd pay 20M for yours. If it had 10 SSI, it would be worth 50 or more.
I think it's very subjective what a pvm player wants vastly different than pvpers needs i think Arnold has great suggestion use vs often i prefer to sell and believe most people want the base items be it clean jewelry or 100% weapons they can tailor make so sell as is maybe package with needed imbuing ingredients etc
It used to be 20mil for clean 10ssi.
If dci, hci, di is included, it can be same price. DI +35 with 10 SSI could sell much higher. I would say 30 or 40mil.
Anything else like stats increase will cause the price to drop to 5mil or less.
So for 5ssi with stats increase, I don't think it's worth more then 100k. I threw mine away some times. It's not hard to get.
For imbued pieces, stats are a waste as the gear can provide those.
What are most needed on jewels are
10ssi
hci
dci
di
slayer
If there is space I rather have
+15 Parrying
+15 Anatomy
+15 Resist
Every bit of resist helps to lower the spell effects.
Not Tactics or Weapon skill as those need 120 real skills to get max damage from mastery.
I'm pretty sure we all know you can't imbue slayers on jewelry or armor.