The spot price of gold that is reported everyday on the Comex does affect the value of rare gold coins-because they are made of gold.  But each coin is affected differently depending on its rarity and quality.  Generally speaking, the lower the quality or lower the rarity of a particular coin, the closer it will be to the spot price of gold.  Vice versa the higher the quality or rarer the particular coin the further away it will be from the spot price.

Rare coins are graded on a scale from 1-70.  This is called the Sheldon scale (quality scale).  Each level in grade represents a higher level of quality.  Investors and collectors alike generally try to achieve high levels of quality for their purchases.  If a coin is a low grade and is a common issue its value will be more affected by the price of gold rising and falling.  If a coin is a high grade and is a rarer issue its value will be less affected by the price of gold.  There are many combinations of quality and rarity, so you can see there are many variables in how the value of a coin can be affected by the spot price of gold.

The most valuable US rare gold coin is the 1933 $20 Saint Gaudens.  It sold for over $7.5 million in 2002.  This gold coin contains one ounce of gold, and at the time of its sale at auction the value of the gold content was around $400.  This specimen at the time was thought to be the only 1933 $20 Saint Gaudens in existence, thus it was extremely rare.  Because of this coins rarity, the value of the gold content is negligible. On the other hand a very fine graded 1924P $20 Saint Gaudens with a population in the tens of thousands, sells for around $1,600 which is only a few hundred dollars more than an American Eagle gold bullion coin.  You can see that the value of its gold content dominates the value of this coin.

Typically, individuals looking for a combination of growth and affordability look to acquire coins in the mint state range with rarity numbers between 1,000 and 15,000 specimens known to exist in a particular grade.  Again, quality levels mixed with rarity will determine value, as well as how fluctuations in the spot price of gold will affect a coins value.  To understand more on how this works speak with a reputable dealer.