You can get 5 Grand Soul Gems for the vampire cure reliably by combining fixed world spawns and a couple of merchants. Here’s a clean, story-like route you can follow in a normal Oblivion (or Remastered) playthrough.

Fastest 5‑Gem Route (Step‑by‑Step)

Think of this as a mini heist tour of Cyrodiil: grab guaranteed gems from display cases, then top up with shopkeepers.

1. Hit the Arcane University (Up to 4 Gems)

Once you have access to the Arcane University:

  1. Go to the Arch‑Mage’s Lobby.
    • There is a display case with 3 Grand Soul Gems behind a Very Hard lock.
  1. Go to the Mage’s Quarters.
    • Another display case there has 1 Grand Soul Gem behind a Very Hard lock.

If you can open Very Hard locks (or use scroll/skill tricks), you’re already at 4 gems just from the University.

Mini‑story hook: many players treat this as their “big break‑in” job—sneaking through the University at night, cracking the display cases, and walking out with enough crystals to cure vampirism.

2. Swing by Chorrol Mages Guild (2–5 Gems Available)

Next stop: Chorrol Mages Guild Hall. Inside are multiple display cases:

  • One case on the main floor has 2 Grand Soul Gems (Very Hard lock).
  • Another case to the left when you first enter has 3 more Grand Soul Gems (also Very Hard lock).

Even if you only crack one case, you’ll easily complete your 5‑gem requirement when combined with the Arcane University haul.

You don’t need every single one; you just need 5 empty grand soul gems, so:

  • If you already looted 3 or 4 from the University, just grab 1–2 from Chorrol and you’re done.

3. Use Merchants If You Can’t Lockpick

If lockpicking Very Hard cases is a pain (low level, no Skeleton Key, or you just hate the minigame), you can instead:

  • Go to Mystic Emporium in the Imperial City Market District.
    • Aurelinwae and Calindil can each sell Grand Soul Gems, and their inventories restock over time.
  • Visit mages guild merchants in various cities; most halls can stock at least one Grand Soul Gem for sale that refreshes.

You can:

  1. Buy what they have.
  2. Wait/rest 3 in‑game days (or 7 to be safe) for inventory reset.
  3. Buy again until you have 5.

There are also quick video guides that show exactly this approach: grabbing a few from locked cases and finishing the count by buying from guild merchants for the vampire cure quest.

4. Extra Fixed World Spawns (If You Want Backup)

If, for some reason, you’ve already looted the University and Chorrol or want alternatives, you can grab additional guaranteed Grand Soul Gems at:

  • Drakelowe – In the basement via the trapdoor hidden in the fireplace, 1 gem.
  • Crayfish Cave – One Grand Soul Gem deeper inside.
  • Nornal – Ayleid ruin west of Drakelowe, 1 Grand Soul Gem.
  • Squandered Mine – Northeast of Drakelowe, 1 Grand Soul Gem behind a secret door on the bottom level.

Each of these holds at least one guaranteed Grand Soul Gem in standard Oblivion/Remastered, which easily tops you up if you’re short.

5. Quick Checklist: “Do I Have 5 Empty Grand Soul Gems?”

For the Vampire Cure quest, the gems must be empty grand soul gems.

Use this checklist:

  • The item name is Grand Soul Gem , not Greater/Greater Filled/Common, etc.
  • The gem’s gold value corresponds to an empty one (filled gems are more expensive) as shown in guides and UI.
  • You have 5 in total in your inventory at once before visiting the quest NPC.

Simple “One‑Trip” Plan

If you just want a no‑fuss route:

  1. Loot 3 Grand Soul Gems from the Arch‑Mage Lobby display case.
  1. Loot 2 Grand Soul Gems from a Chorrol Mages Guild display case.

That’s your 5 empty Grand Soul Gems without even needing to mess with caves, as long as you can open Very Hard locks.

Information gathered from public forums or data available on the internet and portrayed here.