When Neiman-Marcus of Dallas opens next fall in Northwest Washington, a neighbor in the new Mazza Gallerie at Western and Wisconsin Avenues NW will be a small store called A Touch of Silver.

The specialty outlet will feature design jewelry imported from all over the world and will be the third unit in a rapidly-growing retail business started here in 1969 by Henry J. and Marta Oyhenart.

Oyhenart, who started with an investment of nearly $500 and a small store called Hole in the Wall on Connecticut Avenue NW in 1969, is being honored this week as "small business person of the year" for metropolitan Washington by the Small Business Administration.

Now structured as Henry J. Oyhenart & Co., Inc., the Northern Virginia businessman and his wife moved their business from downtown Washinton to Old Towne in Alexandria in 1970 and now operate stores in Springfield Mall and the Crystal City underground center in Arlington under the name of Rio Plata Imports.

Annual sales of the company have grown from $20,000 to about $400,000 as the firm's mix of merchandise has grown to an emphasis on jewelry. Oyhenart at first concentrated on lambskins from his native Uruguay but found that Washingtonians weren't much interested. Then, he and his wife purchased a sewing machine and made the skins into rugs, bedspreads, pollows and clothing.

The new merchandise sold and with the added revenues, semi-precious stones and basic costume and silver jewelry were added, much of it imported from New Zealand, Mexico, Columbia, Brazil, Argentina and Uruguay.

Throughout the development of his small firm, business and financial obstacles were faced: Shoplifting at the D.C. store, the need to refinance a home mortgage to afford relocation to Springfield Mall, redevelopment in Alexandria.

Today, the firm employs 50 persons and Oyhenart is working on an employee profit-sharing plan. According to the SBA, which approved financial assistance for the Oyhenart firm, the local business made use of every possible management assistance program offered by the agency and never has been delinquent in paying off its loans.

In honoring Oyhenart during "small business week," Leon J. Bechet, director of the local SBA office, said the retailer's "pride of accomplishment" helped him over initial adversities. He also paid tribute to Oyhenart's "ability to accept necessary risk factors."

Bechet, whose office is holding a number of seminars and an open house today, said the Washington SBA branch is experiencing a "tremendous upsurge in bank participation" in SBA aid programs for small businesses. Reports for the first two quarters of the current fiscal year indicate that the local office will top last year's total aid (loans and direct contracts) of $52 million by at least 20 per cent, he said.

The largest SBA-backed bank loan in fiscal 1976 was $475,000 for The Design Store in Gaithersburg and the smallest was $5,000 for Photokinetics, Ltd., of Silver Spring. A total of 70 loans for $6.2 million was approved for suburban Maryland firms, 66 loans ($4.2 million) in Northern Virginia, and 100 loans ($7.75 million) for the District.

President Carter presented the national small business award at a Rose Garden ceremony to a boyhood friend, Larry Comer of Americus, Ga., who has built Metalux Corp. into the nation's fifth largest lighting manufacturer. Comer, 44, was born in Plains.