Some people put rugs on the floor, others follow ancient traditions and hang them on walls. Today it's not unusual to find them in both places, as people are buying rugs - especially quality Orientals - as a growing investment.

That's the word from Robert Sarian, a Fort Lauderdale-based expert who three times a year supervises special sales of Oriental rugs at John M. Smyth furniture stores here. The value of Oriental rugs from such Eastern and Near Eastern countries as Romania, Yugoslavia, Pakistan, Afghanistan, Turkey, India, Iran and China is increasing as fewer and fewer people of those countries support the local industry of rug weaving at home.

The reason for this, Sarian points out, is an increased interest on the part of those countries in the education of their people. In Iran particularly, money coming in from oil sales is being used to combat illiteracy.

As the schooling there is free and compulsory, "the kids are leaving the looms and going to school. This means that production of Oriental rugs is going down, and the prices going up. They're becoming an 'endangered species,'" says this expert, who imports rugs for a number of retailers.

Sarian tells of rugs bought years ago for as little as $17.50 that are worth $3,000 now; but this is not true of the rugs made in Hong Kong and Morocco, as "their weaving techniques are different from those in other countries."

Sarian also says the highest prices now are being paid for rugs made in Iran and Turkey, because they are no longer produced as rapidly as in previous years. On some of his trips, Sarian goes into remote villages where families have looms in their homes. "It's a kind of fading cottage industry," he says. "As few as one in seven looms is being operated today."

But rugs made in Pakistan and India still are selling at values close to those of previous years, since the governments of those countries subsidize the weaving industry. At present the American gets the best buy, dollar for dollar, in these depressed areas.

Sarian says that not only are Americans seeking Oriental rugs as investments, but also Europeans are buying them, and the government of Iran has some 200 to 300 agents "scouring the United States looking for old Persian rugs to buy back."

That's for two reasons, he explains. People in that country are affluent and now can afford to buy them, and the nation is seeking them for the museum in Tehran. Those who have Oriental rugs in investment portfolios are finding that some valued at $19 million in '60s now are worth $200 million.

Sarian cited the comparison of rugs reported in a 1974 survey of Business Week magazine, which showed that in constant dollars, they had gone from $100 to $750 in five years, while American stocks had gone from $100 to $90 in that same period.

What are some of the patterns that are more valuable than others? Sarian says that geometric patterns are scarce, and in some regions florals are as valuable. Kerman designs are very popular and difficult to find.

The current best seller among Oriental rugs is the silk prayer rug. Tightly woven, yet almost delicate, these rugs are ideal for wall display, which is really the best way to preserve a rug, advises Sarian. "These are the Rolls-Royces of the industry and are zooming in price."

Obviously, second-and third-quality rugs are not good investment risks, he adds, emphasizing the importance of knowing the company from which a person purchases an Oriental rug, regardless of whether it is for investment or purely for the joy of owning one for home decoration.

"If you don't know Oriental rugs, be sure you know the person who sells it to you," he cautions.