Per EQ Traders: This item can be Vendor Purchased:
* Abysmal Sea o Glirina Morningbloom @ -142, 228, 98, in the hold o Rilwind Sitnai @ -163, 200, 98 * Ak'Anon o a clockwork jeweler @ 1348, -884, -28, in bank * Cabilis East o Klok Ixmid @ 659, 156, 6 * Crescent Reach o Jeweler Nailah @ -1247, -1648, 33, upstairs in The Jeweled Serpent * East Freeport o Ennuard Yetaius @ 692, -530, -10, in Arena building o Ilenarn Ghaeaus @ 653, -527, -10, in Arena building * Echo Caverns o Solsain Paslinor @ 1324, -544, -78 * Firiona Vie o Drake Mountainstorm @ 896, -3335, 159 * Grobb o Rezslog @ 455, -179, -2, Outside Krungs Clubs & Junk o Uzak @ 563, -319, -2 * Gukta (in Rathe Mnts) o Zok Prolo @ -1900, -189, 2 * High Keep o Merchant Edina @ -97, -294, 5, Upstairs from the bank * Icewell Keep o Coldain Outcast @ 52, 928, -21 * Kelethin (in Greater Faydark) o Merchant Laedar @ 617, 542, 163, EQAtlas platform #5 * Neriak - 3rd Gate o Telnor D`Unnar @ 807, -1419, -78, In The Bauble * Neriak - Commons o Nekola N`Ryt @ 81, -931, -24, Inside Forge House * North Kaladim o Banaf Norkhitter @ 699, 426, -63, in the mine * North Qeynos o Svena Ironforge @ 60, 34, 3, inside The Jewelbox * Northern Felwithe o Merchant Tyslin @ 107, -439, 19, Upstairs, Shop of All Holos * Overthere o Tin Merchant IV @ 2647, 2525, -48 * Plane of Knowledge o Kirem Deepfacet @ 423, 769, -92, Northern trader building * Rathe Mountains (see also Gukta) o Darfumpel Zirubbel @ 4093, 896, 4, Inn in northwestern section * Relic, the Artifact City o Goroth @ 933, 377, -274 * Shadow Haven o Adinson Allonode @ -12, 631, -44 o Pilop Stolarix @ -716, 1576, -62, Inside small stone hut near House of Stout bank o Eriska Malosona @ 1175, 44, -46, upstairs in library area * Shar Vahl o Uhlma Mareesh @ 216, -371, -187, Inside middle northern building in Merchant's Quarter (bags, barrels, and boxes on sign) * Southern Felwithe o Merchant Tyslin @ 450, -775, -2, inside merchant building * Steamfont Mountains o Torodrane Frompwaddle @ -1602, -1841, -109, At the southeastern Observatory * Thurgadin o Meg Tucter @ -350, -54, 3, Inside jewelry shop * West Freeport o Jade @ -159, -1319, -137 o Aimie Moonspin @ 436, -696, -87
Pretty sure there isn't one. I got decent drop rates in Dranik Scar. Depending on your level pretty easy to farm. I was killing Noc's, Kyv's for faction and got several off of these. So there's more mobs in Dranik's than listed. Unfortunately I don't remember for sure exactly what mobs they were. I know it was the Noc's or Kyv's, as I was killing those for faction.
"Opal" was retrieved from the still flickering corpse of a willowisp in Jaggedpine Forest. The Wisp also dropped Words of Convocation and a Greater Lightstone.