Watch List notes:

BRITISH COINS, IRELAND, James II, Gunmoney Halfcrowns (2), large size, Sepr 1689, small size, May 1690, thicker flan than usual, 11.44g (S 6579D, 6580CC). Both about very fine with some patches of verdigris, toned. (2)
The May 1690 piece is approximately 2.0g heavier than another example of a May 1690 piece currently in the Baldwin's stock trays.

Estimate: £80-100