Sorry Chris, I didn't mean to knock you!    I responded in a tongue-in-cheek fashion - it was quite wrong of me rib you in that manner.  I think it being made of plastic is an excellent idea.  No plastic will register on a metal detector, and while the size and sharpness would lose nothing, the lightness of a plastic "coin" would give the game away immediately.

A lot more difficult to determine would be the authenticity of not only medals but horse furniture - brasses, crotel bells etc.  that sort of thing.  Most places along Portebello Road are on the level, although you'd get no bargains - you pay top prices in that area.  Keep your eyes skinned at boot sales - not collectors fairs.  Again they tend to inflate the prices.

Once again, no offence meant - it's my droll sense of humour.

Peace be with you.  Your Brother in Christ.   Fred  (Born-again2003)