hello John - at great risk of getting it wrong again

.........certainly this is both the correct shape and colour for a Nazeing piece - the colour being from one of the group of 'lilacs and purples'.
You don't mention whether your piece is cased in clear, and would be interesting to hear what sort of pontil depression it has.
I know we've had these on the Board previously, so you might get more information by using the search and trying under Nazeing.
