Mexico has issued a lot of cool coins in modern times, and, like some other countries, they issue them in gold and silver which makes them more valuable that plain face value. You can actually invest in precious metal by collecting Mexican gold and silver, but you have to understand some basic rules before you shell out hard-earned cash.
Mexico went through a period of hyper inflation between 1985 and 1993, so coins minted before 1994 tend to have very large face values. In 1994 1000 old pesos became 1 new peso.
CoinQuest has written quite a bit about investing in gold and silver these days, but there are a few twists with Mexican coins that are worthy of note. If you are interested, read further about the Mexican twist, then proceed on to our gold and silver page which is referenced at the bottom of this page.
The fundamental aspect which you must understand about collecting and investing in gold and silver coins is how to compute the actual weight of pure preciouse metal in a coin. Some coins, Mexican or not, are made of pure gold or pure silver. Some coins are made of alloys of gold and silver. Only the actual gold or silver weight applies to value calculations.
For modern Mexican coins the weight of gold or silver is imprinted direclty on the coin itself. For instance, you will see inscriptions such as:
1 onza de oro ley 0.999
1 onza plata pura ley 0.999
These inscriptions mean, respectively, one troy ounce of pure gold and one troy ounce of pure silver. The 'troy' is understood when dealing with precious metal, and it is different that 'avoirdupois' ounces which is what you get in America when using normal ounce measurements of, say, foodstuffs.
The 'ley' in the inscriptions above refers to purity of the precious metal. Ley 0.999 is (essentially) 100 percent pure gold or silver. But you might see a coin with a purity of 'ley 0.720' which means there are other metals in the coin and the precious metal is only 72 percent of the total weight.
We are not quite finished with the Mexican twist! Sometimes weights are given in grams and not in troy ounces. You need the weight in troy ounces to compute coin value. There are 31.1 grams in a Troy ounce.
A 100 pesos ($100) silver coin from 1978 bears the inscription:
plata pura 20 gr ley 0.720
To figure value, we need the actual silver weight. There are 20 grams of pure silver in the coin, so:
20 grams / 31.1 = 0.643 troy ounces of silver
The 'ley' purity is only 0.720, so other metals are mixed with the silver, but the pure silver weight is 20 grams or 0.643 Troy ounces. Using a web site such as kitco.com, we find the current price of silver is about $17 per troy ounce (the price changes every day, look it up), and the value, then, of 0.643 ounces is 0.63 x 17 = $10.90 US dollars.