Serpent Spine Diamond  

 

i cannot say for certain, however i have been doing jewelcrafting since before the first anniversary of everquest, and as of 2013 i cannot find any information on serpent diamonds in game or out of game.

i tried to combine with gold bar like other diamonds and faydwer and serpent diamonds are near the level of other diamonds and the game doesn't let you combine like other diamonds. the diamonds may be used in tradeskills but there is no information to support this in or out of game, so until someone writes how or posts how somewhere, you have to assume that these are vendor trash. remember that some things combine with gold but not with silver and electrum to improve jc easily. it's not like i don't have the skill. when i don't have a skill but something is combinable the items disappear, but when there is no game recipe, the items don't disappear. the items didn't disappear.

the bottom line is to vendor the diamond. there are enough recipes and diamonds for jc that you don't need to hold on to this diamond for any reason when the sell value is decent for a stackable item. the only possibilities i didn't try are that you might be able to use an enchanted gold bar with the diamond, or there is a recipe with 3+ items that uses this.

not worth any tribute

Can anyone with firsthand knowledge confirm whether these are only vendor trash or if they can be used in tradeskills like jewelcrafting?

I got one off Taruskor (named mammoth) in Icefall Glacier

Just looted from 'an animated icepile'
Sell for 279p, 4g, 2s, 9c at vendor