The word ‘torc’, as in ‘Leekfrith torcs’ is not in Benson, nor in Wells, nor in Vikivotaro, nor in ReVo, nor in Sonja’s English-Esperanto dictionary. So, how should this word be rendered in Esperanto?
I see this question as an opportunity to discuss some deeper topics about vortfarado as it works in very many languages, invented or not. Essentially, what you do is to define a whole class (say, “farmers”) by means of one feature, which you select as typical (e.g. “living in the countryside” = kamp-ar-anoj). The other features (e.g. “getting their income from agriculture”) are implied. In advanced Esperanto courses this is usually described with the sentence “There is more in the whole than the sum of its parts”.
This mechanism makes it easy to achieve fluency very quickly: it is much easier to remember kamp-ar-anoj than completely unrelated words like field, countryside and farmer. However, there is a price to pay: when you actually need a word for people living in the countryside without the other connotations, kamparanoj is already taken and you have to use kampar-loĝantoj, which hasn’t undergone lexicalization and is so heavy that it probably never will.
Now, you really don’t want to lose important, lightweight, everyday expressions like kolringo or tordaĵo to the obscure, niche meaning of torc. You can decide to use them for a one-time translation, but it will be a description, not an identification.
In my opinion, if you want to permanently identify a class of specific objects from a specific cultural landscape, a particular region or a well-defined period in time, the best way out is to use a new primitive root for them. Vikipedio proposes torko. This is the word to use and hopefully it will soon be in our dictionaries. It is only fitting that its creator, Lvh, lives in Celtic land, and, yes, she is a kamparloĝantino.
As it comes from Latin torquis, "twist", I would consider the Esperanto tordo. If you want to clarify that it is a neck ring, torda kolcxeno might also be an option.
Tordo on its own has of course the potential for confusion, but similarly, torc is not a word many people would understand without explanation.