Here's a MUCH better idea:
Have a box set up similar to the various collection/spring cleaning events.
If you drop a full soulstone on it, it takes the soulstone, and does the following:
1. Credits the owner account of the soulstone with a replacement anniversary gift (they'll lose the skill on it, but at least they can choose to re-take the stone).
2. The stone's owner will get a message on next login that their stone has been recycled into a new vet reward pick.
3. A person turning in someone else's stone gets 10 credits in the system. Turning in your own only results in your getting to rechoose the reward (allowing a person to turn green or blue full soulstones into additional vet rewards).
4. Rewards for turning in soulstones: A soulstone fragment could be claimed for 10 credits; a full soulstone (choice of color) is a 50 credit reward, as is a vet reward additional pick.
5. Other items could be added to the list. Soulstone fragments (and fragment tokens) could be 1-3 credits (1 credit for 0-1 charges left, 2 for 2-3 charges, 3 for 4-5 or a token); other non-deed vet reward items could be varying amounts (1 point per year for vet clothing and statues, 2 points per year for Ethys, etc.), making this a system where you could reduce the total number of vet rewards flooding the shards, by having them turned in for other items at reduced value (as it would take 50 first-year statues and robes to get 1 new pick).