All that glitters is not gold. It may be silver, or even copper.

Most people are aware that the spot price of gold recently hit $340 a Troy ounce. Although gold has increased 64 percent in the past year, you could have doubled your profits if you had invested in silver instead of gold. Since September 1978 silver has skyrocketed 132 percent to over $12 an ounce.

Mercury has defied its volatile nature by jumping steadily upward to $295 a flask, a gain of 87 percent in a year. Platinum's finish has been anything but dull these past 12 months, up 57 percent to $425 an ounce. Finally, the penny may not be worth a copper to the consumer, but to the investor that commodity is no longer a base metal after its 55 percent increase during the same period.

Metalmania has possessed the world in recent weeks. Traders warn of panic buying, of a snowball effect starting with ghold, of political and economic instability at home, and high demand abroad (read Middle East) -- as well as an imminent decline in overinflated prices.

Officially, so far as the U.S. government is concerned, gold is just another commodity, something in a class with, say, pork bellies or Maine potatoes. Of course the rest of the world considers it the most desirable of all precious metals. So, how would gold stack up as an investment in a classier, albeit fictitious, futures market?

The wise man who bought frankincense two years ago would have realized a 200 percent profit. That biblical essence, now called olibanum, is today worth $125 a pound, its price the victim of wars in Ethopia where it originates. The myrrh market, incidentally, remains stable at $95 a pound. But rose and jasmine essences, the stuff of which $135 an ounce perfume is created, now brings $2,500 a pound in France, according to J.P.M. Imports of New York.

Among the cosmestibles, Iranian caviar barely kept pace with inflation, up a mere 11 percent to $17.14 a spoonful -- uh, ounce -- while Italian truffles remained unruffled at$25 an ounce, according to New York purveyors. In the underground economy, the price quoted on the street -- 14th not Wall -- for pure heroin rose by one third during the past year, whereas cocaine cost just 10 percent more. The amount of pure heroin in a $50 bag would make a Troy ounce of the stuff worth $70,000, 206 times the price of gold! Pure cocaine on the street works out to $20,200 an ounce, courtesy of the Drug Enforcement Administration.

And, should you be interested in a different kind of high (price), an ounce of powdered rhinoceros horn commands between $300 and $500 in Hong Kong markets. The outlook for this Asian aphrodisiac is an increase in price now that its sale is illegal, the rhino being an endangered species. So, too, with elephant tusks, the price of which has increased 25-fold in nine years to $60 a pound.

For some investors the switch from commodities to collectibles is as easy as a flip of the coin. The number of U.S. numismatists has jumped from half a million in 1954 to 12 million in 1978, and the volume of the coin market more than doubled in four years. Not coincidentally, coins have been appreciating at the rate of 13 percent a year during the past decade, while pre-1933 uncirculated coins are rolling along at 29 percent per annum. A dealer recently bought a 1927D $20 gold piece for $250,000 and resold it the same week for $300,000. A 1787 gold colonial coin called the Brasher dubloon set a record last month by bringing $430,000.

If gold dollars are beyond your means, try aluminum cents. American Collector magazine's October issue tips its readers to the pot of gold awaiting the lucky person who finds one of the dozen missing one cent pieces out of 500 produced on an experimental basis by the Philadelphia Mint in 1974. The trail leads to Capital Hill where legislators, having looked over and rejected the proposed copper replacement, then forgot to return the pennies.

Diamonds are everybody's best friend, according to American Collector's survey last July of 700 people. Nine out of 10 thought the value of diamonds would do better at keeping up with future inflation than the family budget. No doubt they were dazzled by their brilliant past record as well as the rhinestone smiles of mail order merchants. Yet Salomon Brothers, the New York investment bankers, calculated that diamonds appreciated only 4 percent last year, compared with an annual rise of 12 percent over the past decade.

Ironically, less than half the collectors picked stamps as inflation fighters, whereas the bankers estimated investment-grade stamps went up 60 percent last year, second only to silver. All agreed on gold, antiques and china.

Oriental rugs have been flying monetary carpets during the past decade, the most precious ones soaring as much as 2,000 percent as the supply declined. They have now leveled off -- nomadic rugs led the way last year with a 25 percent increase -- and dealers believe that any action by the Ayatollah to change the currency will force exiled Iranians to liquidate their carpets for cash.

Oh, you say you just spent $30,000 on an 18th century Caucasian Dragon and are looking for some more modest investments. American Collector offers a few suggestions:

Clocks: value doubled in the past two or three years. Campaign buttons, especially those with a presidential and local candidate; Cox-Roosevelt button now worth $2,000; Adlai Stevenson and Mayor Daley now worth $100; Carter and anybody in 1980 will become collectors' items.

Baseball cards: tripled in value in past three years and will continue to rise; Babe Ruth and Lou Gehrig cards now worth $50. Pre-Prohibition beer trays: worth $50- $75 five years ago, now $125 and up, will double in next five years. Brazilian opals: worth $1,500 a gram.

From the classified advertising section comes these bargains: first edition Life magazine in mint condition, $30; Shirley Temple 27-inch doll, $595; and a signed, nude Marilyn Monroe photograph, $180. As for tomorrow's opportunities of a lifetime, how about old stock certificates, old fountain pens or even old fishing tackle? Expect a market in John Wayne memorabilia a la Elvis.

Finally, here's an inflation fighter that's as all-American as Currier and Ives prints or Gerry Ford's WIN button -- turn-of-the-century cigar box labels. According to The Wall Street Journal, stogie lithography, featuring the requisite Indians, cowboys and women, but also "gesticulating wizards," has appreciated about 500 percent in the past year. Individual matted labels that were selling for $1.50 to $3 now bring $5 to $15 unmounted and $20 to $70 framed.