(Read more: As reality sets in, gold will decline: Pro)
Technically speaking, of course, gold is considered a commodity as it can be used for a variety of purposes but most often for jewelry.
For trading purposes, though, it moves like a currency and should be treated like one, Gartman said.
Currencies trade one against another, like the U.S. dollar against the euro or the Australian dollar against the yen.
In gold's case, it performs best when measured against the world's weakest currencies, making it a good bet against the yen, which is being devalued as part of the nation's efforts to resuscitate exports and jumpstart its economy.
(Read more: Gold bulls unfazed even as stimulus-led rally fades)
"The (Japanese) monetary authorities have..told us without equivocation that they are going to expand the monetary base by at least double," Gartman said. "All things being otherwise equal, if you're going to have to be bullish of commodity prices generally try to be bullish of them...in terms of the Japanese yen, because the Japanese have no choice but to devalue their currency."
"You still want to own gold in yen terms, though you may not want to own gold in dollars," he added.
Gold advocates believe it is a good protection against inflation
Even so, Gartman said investors should be wary of anyone who tells them they should have gold in their portfolio simply as a safe haven.
"Gold is not a safe haven," he said. "Anybody who tells you that is a charlatan at best and a liar at worst. Safe havens do not move 2 and percent in value during a day."
The timing of his comments was interesting—one of gold's loudest advocates, Euro Pacific Capital CEO Peter Schiff, was slated to speak later in the morning.
(Read more: Here's how you'll know the gold plunge is over)
Elsewhere in the currency space, Gartman said energy prices are likely to climb long-term because they are in backwardation status—the future contracts are trading lower than the current price.
He also said investors should watch crop reports.
Soybean acreage is expected to increase dramatically next year at the expense of corn and cotton. Gartman recommends investors be long of cotton and short beans for the 2015 contracts.
_ By CNBC's Jeff Cox. Follow him
@JeffCoxCNBCcom on Twitter.