The Hearts of Potosí 

Silver cobs come in all shapes and sizes, most by chance—but a few not. The ones that are deliberately shaped come in three types, all special presentations from the mint: round “Royals,” haphazard zoomorphic shapes and grandiose “Hearts,” the latter two types only from the mint of Potosí, Bolivia. Determining whether a “Heart” (corazón in Spanish) is authentic can be difficult, and there are certainly more counterfeit Hearts than genuine pieces. But while a counterfeit is just a mutilated cob, the real thing, in any denomination, can be worth tens of thousands of dollars (or more).

The Hearts of Potosí were minted in five denominations: ½, 1, 2, 4, and 8 reales (though half-real Hearts are so rare that only a handful of pieces have been confirmed), and apparently only from the very late 1600s (the reign of Charles II) to the mid-1700s (the reign of Philip V). The outline of a corazón can vary significantly, but it is basically Valentine-style yet with a wide, tall stem and a long, tapering tail. Predictably, almost every confirmed Heart has been holed at the top of the stem. Unlike most holes in cobs, these may have been mint-produced holes.       

We don't know for sure why cobs were cut into heart shapes at the Potosí mint, but given their scarcity, their usually careful execution, and their tendency to be holed, they were most likely produced for special use as religious pendants known as “ex votos.” The prevailing theory is that they were intended to be used by church officials, as the heart was known to be a sacred symbol of the Roman Catholic Church. It is also believed that women sewed these images of the Sacred Heart of Jesus Christ into their blouses, a custom which is still observed in remote Andean villages today.    

[Note: The Catholic Sacred Heart symbol, as demonstrated in ex votos and other manifestations, is in fact a flaming heart, usually with a long, curved tail. This matches the Potosí Heart cobs precisely, their prominent stems at top apparently representing flames.]    

With all the minor variations in heart shapes, counterfeits would seem impossible to detect given that anyone outside the mint could simply carve up a silver cob into the desired configuration at any time. But such mutilation removes significant amounts of the prescribed weight of the cob and, for that reason, the most reliable authenticating aspect of a genuine, mint-produced Heart is its full weight. A genuine specimen can still be slightly underweight or overweight, so other attributes must be examined:

1. Does the planchet extend beyond the imprinted design, including the legend, of the coin? Whereas fake Hearts are cut down from regular cobs, the authentic pieces are struck on intentionally oversized planchets to make up for the subsequent loss of metal while filing them down to the heart shape.

2. Is the design carefully executed? Most Hearts appear to be struck from “Royal” dies which were also used to strike special round presentation pieces purportedly produced for the king of Spain.

3. Are the cross-side and pillars-side axes aligned? Most genuine Hearts show straight-up-and-down orientation on both sides, with the stem at the top, an alignment that seems to indicate that they were made to be worn as pendants.

These criteria are by no means definitive, but they may serve as guidelines for the novice collector or student.       

Once you know that your corazón is genuine, you also know that you have a rare and very valuable cob. (For example, in 8 reales there are only about 30-35 pieces known—see table below.) The worth of a Heart is, of course, greatly dependent upon its beauty, and a range of values exists for all denominations except the ½ real, which is too rare to evaluate. The most common, or rather least scarce, denomination of Heart is the 1 real, whose value can range from about $2,000 to $4,000. Two-reales Hearts are next in value from about $3,500 to $11,000. Then the price jumps to about $8,500 to $27,500 for a 4 reales, and no cheaper than $25,000 and as much as six figures for an 8-reales Heart.

Hearts are not for everyone. The prices are understandably restrictive, and one could easily spend a lifetime (and a fortune) assembling a decent 1-2-4-8 reales set of Hearts. But to the avid collector, nothing brings out the primitive beauty of a cob like a Heart, regardless of the cost.

Cover of The Practical Book of Cobs, 4^th edition (2007), showing a

Potosí, Bolivia, cob 8 reales Heart, Louis I, 1726Y.