until the other day I didn't know the word existed - to me things are either blue, green, turquoise, teal etc. etc. Apparently cyan comes somewhere between blue and green - has various tints and is often likened to a paler form of teal.
Presumably an inkwell of sorts - whether is once formed part of a portable or static garniture of writing kit I've no idea - the top is a base metal that's degraded somewhat (unmarked) - polished surfaces and all the arises beveled, and with one or two flea bites on edges. Perhaps the colour was to remind you to refill with blue ink rather than black or red. It has a side of c. 1.5 inches (about 40 mm) and about 2 inches tall. Un-attributable, in the extreme, I'm sure, so no need to go there, but wondered if people might like to take a stab at age - and of course the colour is v. much worth looking at.