Valyrian Steel in the Citadel [duplicate]

Question

It is revealed that the Maesters have acess to Valyrian Steel when Maester Luwin shows Bran his Valyrian steel link. We are told that when Maesters learn a new skill, they forge a new link, I assume this is literal.

Marwyn the Mage, also has a Rod, ring and mask of Valyrian Steel. I assume the mask and ring would be reforged every time a new arch maester is appointed.

These pieces of evidence show that the Citadel does have a seemingly large stockpile of Valyrian steel and that perhaps, they have someone who can rework it. Tywin says that there are only three living smiths capable of doing so. Is there any direct reference to a stockpile of Valyrian Steel in the Citadel or a Maester who knows who to rework it?

Answer 1

GRRM has answered at least part of your question:

Fan: Do maesters fully forge the links of their chokers from raw metal, or do they take strips of existing metal and forge it into the links?

GRRM: When he said a maester "forges" his chain, it is more metaphorical. They do study metals, but that doesn't necessarily include training as blacksmiths.

Fan: I had assumed the former, but the latter would be simpler. I ask, of course, because of the link of Valyrian steel in Maester Luwin's chain. Did he know the spells, or did he take an existing strip and beat it into shape?

GRRM: He studied magical tomes and histories, and mastered enough of the arcane lore to impress an archmaester into granting him a link. He did not necessarily have to make the steel himself.

Answer 2

As for if the Maesters can reforge Valyrion steel themselves, I doubt it. The only people in the known world who claim to know how to rework Valyrian steel are those in Qohor.

Only here, in all the world, has the art of reworking Valyrian steel been preserved, its secrets jealously guarded.
...
Maester Pol's treatise on Qohorik metalworking, written during several years of residence in the Free City, reveals just how jealously the secrets are guarded: He was thrice publicly whipped and cast out from the city for making too many inquiries. The final time, his hand was also removed following the allegation that he stole a Valyrian steel blade. According to Pol, the true reason for his final exile was his discovery of blood sacrifices—including the killing of slaves as young as infants—which the Qohorik smiths used in their efforts to produce a steel to equal that of the Freehold.
_{The World of Ice and Fire, The Free Cities: Qohor}

As I cover here that is why Tobho Mott is likely Qohorik and so how he knew how to rework the metal.

---

On a side note this trend is actually broken by the show when an unnamed Volantene blacksmith is used to reforge Ice. This was because the actor who played Tobho was unavailable.