Cased coin proof set, British Virgin Islands, 1 Dollar / 50 Cents / 25 Cents / 10 Cents / 5 Cents / 1 Cent, copper alloy / silver, made by the Franklin Mint, United States of America, 1979
Proof sets are specimen examples of coins produced generally for collectors. Using highly polished blanks (planchets) and specially prepared dies to accentuate detail, a special process involving 2 strikings from the coin press at increased pressure produces a very attractive cameo effect and mirror like surface. Occasionally a frosted section is included, most commonly on the raised design but alternatively on the flat background.
Reference: Krause, Chester et al. 1996 Standard catalog of world coins, 23rd edition, Krause Publishing Inc, Iola, Wisconsin, USA, 1995, p. 282, PS 9