Is a 1986 50 proof gold coin worth more because it is a proof coin?

Proof coins are always worth more than the circulating coins they resemble. Mint collector coins are different than circulating coins and need to be valued differently. Mint coins can come with several various types of surfacing, proof being one, bullion, burnished and brilliant uncirculated the others.

The $50 gold coin has no circulating counterpart. It does have a similar brilliant uncirculated counterpart however. While ordinarily proof coins are more valuable than similar brilliant uncirculated coins this is not always the case. The lower amounts of brilliant uncirculated coins minted can cause these to become more valuable than the proof variety for the same year. 1986 had a relatively low minting of brilliant uncirculated collector mint coins and they are, for this and a few other years only, more valuable than the proof varieties.

As is always the case with collectible coins, condition affects value. Hence any collectible coin needs an accurate assessment of condition before a specific value can be assigned. Values for these type collector coins are represented in "The Red Book" a semiannually published book listing US coin values.