Guild Wars 2

It would be the equivalent of a gemstone, I think, or perhaps a rune with those stats. I can’t find any indication of it when googling.

http://wiki.guildwars2.com/wiki/Exquisite_Charged_Ambrite_Jewel it’s a jewel so you can only put it in trinkets

If you want a rune that works well with sinister stats try http://wiki.guildwars2.com/wiki/Rune_of_the_Aristocracy

For armor, my engy has thief runes as they increase similar stats that sinister does. (http://wiki.guildwars2.com/wiki/Rune_of_the_Thief) For all 6 you get 175 Precision, 100 Condi Damage, 10% damage when flanking.

Aristocrat goes well with sinister for necro