It is very glossy/shiny, and I agree with Stef that the chunky pieces could be real Whitby jet, but vulcanite was often polished to a high lustre and although it never appears quite as shiny as jet, it can appear very shiny when it is new, and if it has not deteriorated over the years it can still retain a high lustre. It was particularly used in the later 19th century in the UK to imitate jet, especially jewellery, so we do see more of it over here.

What are important are the links, so have a look at Muller's figure 7.11 where specimen vulcanite links are shown - they nearly always have one slit and could be sprung open and closed when new. Real jet chains are made of either solid links with no slits, or with two slits where they have to be pinned and glued together (as in Muller's fig 5.32).

The image here is a genuine vulcanite chain and you can not only see some of the single slits, but also that this one has a characteristic yellowish tinge from the highly lustred black surface deteriorating over the years from what it originally looked like. Although it originally would have looked like a jet chain, it doesn't now, whereas real jet would not have altered.

I will try and look out some vulcanite beads whose surface hasn't changed as much as this.

Carole