Is This A Genuine 1887 British Halfcrown ?

Thanks for the replies on the crown and double-florin.

At a recent country sale I bought 2 specimens of 1887 short currency sets (not in cases) plus extra young head sixpences and threepences.
The quality of most of the coins is unbelievably good.

I paid about half catalogue price and thought I did well, but now I'm not so sure.

I'll post photos of each in separate posts.

Here's one of the coins:





Using a Myco electronic balance the weight is 14.2 grams.