Are stocks always the best long-term investment?

Maybe not.

When some obscure Hawaiian stamps from 1851 go up for auction later this month, they are expected to fetch from $50,000 to $75,000 each.

And if they do, that will mean they have almost certainly been a better financial investment — probably a much better investment — over the past 165 years than the U.S. stock market.

The 13-cent so-called “Missionaries” were used by Christian missionaries in the Hawaiian islands to send letters home. At the time, Hawaii was an independent kingdom. The Associated Press reports that the stamps are part of a 77-stamp collection being sold by Bill Gross, the bond market guru. Ten such “Missionaries” in near-mint condition are being sold.

If the stamps sell for $50,000 each, that will represent a compound annual return of 8.1% over the initial 13-cent purchase price. If the stamps sell for $75,000, you can raise that to 8.4%.

And although accurate financial data from the Victorian era is hard to come by, that looks way better than you would have earned over the same period from the stock market.

According to data compiled by the Federal Reserve Bank of Minneapolis, consumer inflation since 1851 has averaged 2% a year, meaning that these stamps have earned more than 6% a year in so-called “real” terms.

Stock market cheerleaders claim that’s also what you would have earned from equities over the same period.

But here’s the problem: The stock market investor never actually got that “6% real return.”

They had to pay brokers’ and money-management fees every year, and for most of that era, there were no low-cost mutual funds. Not long ago, you typically paid at least 1% a year in fees, and if you go back further in time, the fees were higher still. There were few investment funds in the Victorian era, so they had to buy a broad basket of stocks on their own, and that was costly in trading terms. Financial disclosures were so bad that you had to spread your money very broadly to cover your risks.

And, bluntly, stock market data from before World War I is pretty shaky anyway. There are way too many uncertainties. We don’t really know what investors actually earned, despite our best efforts.

Meanwhile, we know exactly what investors earned from a Hawaiian Missionary stamp. We know the purchase price: 13 cents. And on May 29 at New York’s Javits Center, we will find out the present value.

None of this proves that stocks are a poor long-term investment or that stamps are a good one.

Nor does it mean that you should cash in your index funds and buy stamps.

However, it should provide a healthy antidote to the simplistic claim that stocks are always the best long-term investment. Be aware that very few money managers know anything about financial history. You’re lucky if their knowledge goes back to 1981, let alone 1851.