How to create a Lacquered Fire Opal
Lacquered Fire Opal are created through Jewelcrafting (Trivial is 110) with all vendor bought ingredients. The Fire Opal that we need is purchased from basically any Jewelry Supply vendors throughout the game. The Jar of Lacquer on the other hand is sold by a different NPCs with seemingly no real pattern. A list of some vendors that sell the Jar of Lacquer can be found below.
Once you have both ingredients to make this item, place them in a Jeweler's Kit and hit combine.
Blacksmith Gerta & Borik Darkanvil - PoK (Smithing Supplies)
Borik Darkanvil is one of the Smithing Supplies vendors that was added into the game during the Planes of Power expansion pack, so, immediately when Plane of Knowledge goes live on your server. There are additional Smithing Supply NPCs inside the same building that Borik is in. Use Find if you're having trouble locating him.
The other NPC shown above is Blacksmith Gerta who won't be added into the game until during the Call of the Forsaken expansion pack.
Ethruncil Draitia - East Freeport (Eucalyptus Leaf Vendors)
If Planes of Power isn't live on your server then this is the next best place I recommend you go to purchase Jar of Lacquer. If you're unfriendly to the humans or traveling this far would be an inconvience to you... Just make a level 1 Human and put money in your Shared Bank.
This'll allow you to still purchase Jar of Lacquer from this vendor just without all the extra hassal of running here or having to be good faction with the Humans that live in Freeport.