The gems used for itemupgrades Options

[Shaitan]

This list I use to use a lot when playing IA:

These gems/necklesses are used for itemupgrades - as per the title - and thus you might want to carry them with you or save them for later:

48-sided Garnet
Aquamarine Gem
Beljurils
Bloodstone Gem
Bluestone Neckless
Chrysoberyl Gem
Diamond
Emerald
Fire Agate Gem
Fire Opal Ring
Golden Star Garnet Gem
Horn Coral Gem
Iol Gem
King's Tear
Laeral's Tear Necklace
Pearl Opal Gem
Red Coral Gem - (this is a gem you created right??)
Rogue Stone
Skydrop Gem
Star Sapphire Gem
Water Opal Gem
Ziose Gem

[Sikret]

Red Coral Gem - (this is a gem you created right??)

Yes, this and these two as well:

48-sided Garnet
Golden Star Garnet Gem

Red Coral Gem and the 48-sided Garnet are unique; there are three Golden Star Garnet gems in the entire game.

Having such a master list of required gems is useful to know which kinds of gems to keep and which to sell. It's even good to add the maximum numbers of each type you may need in the game to the list so that you don't unnecessarily keep too many of each type in your inventory. (Of course for some of them there is no definite maximum required numbers; for example, the Laeral's Tear Necklace can be used to upgrade protections cloaks and the number you need depends on the number of cloaks you want to upgrade.)

Also, keep an eye on your cash. If you spend too much money on small upgrades, you may eventually face financial problems for the major and expensive item upgrades.