the wiki says that anvil material and quality does not affect the quality of the items forged with.
at last for the material, im quite sure that this is not correct.
on my current fort my armorer forged some hundred of coppercaps to practice his skill. he made quite a lot of masterworks, about 30% on higher levels.
after i discovered i have hfs, i started to make some admandite armor pices.
altrough my armorer was lv 25 meanwhile (he went moody just after hitting legendary) the produced armor pices where only verry rarely of masterwork quality (somwhere like 5%)
while i´m some sort of a child of misfortune, i started to wonder if it realy was only hard luck. so i made myself a masterworked admandite anvil and forged some more admandite armor.
guess what: suddendly about 30% of the produced pices where masterworked.
i experimented some more, also with iron and steel anvils and this is what i think is happening:
1:
when forging material of a higher quality (maby higer meltpoint) on a anvil of lower material quality, the resulting items will bemuch less likely of the highest quality the worker culd achive with his skill. the items will not have a lower quality than the worker culd achive with his skill, however.
2:
when forging material of a lower quality on a anvil of higer quality, the worker will not produce items of a higer quality than one wuld expect from his skill.
3:
im clueless if the quality of the anvil (if its a masterwork or basic-quality) will affect this. more testings wuld be needed.
4:
as all these results are higly affected by fortuity, i can not be sure that my observations are true. all i can say is, that - according to my observations - it is verry unlikely that the anvil material is NOT affecting the item quality.