Things were different on Washington Street in downtown Boston when Leon Ohanian opened a jeweler’s shop there in 1919.

The street teemed with shoppers — enough to keep the Armenian immigrant and his family busy cutting diamonds and selling fine jewelry for three generations. The building that houses their store in Downtown Crossing once played host to several floors of artisans specializing in gold, silver, jewels, and engraving.

Today, the old Diamond & Jewelers Building has numerous vacancies and elevators open onto some empty storefronts.

Even as luxury condos rise nearby, bringing wealthy new residents to the area, Eric Ohanian, Leon’s grandson, worries it may be “too little, too late’’ for merchants who have withstood years of urban blight, a void after Filene’s left, and Internet competition.

“I’m thrilled that the area’s changing for the better. It’s about time,’’ says Ohanian, 60, who runs the business, Leon Ohanian & Sons Co., with his cousin, Gregg, and still keeps index cards with notes on the jewelry his clients like best. The well-worn tools their fathers and grandfather used to grind the world’s hardest stones fill a back room in their store.

On Monday, the duo helped a young woman getting her fiance’s wedding ring, and a longtime customer picking up a necklace for his wife, marking their 60th wedding anniversary. At their peak, in the 1990s, they did $2.2 million in sales annually.

Today, sales are about half what they were then, Eric Ohanian says, and margins are slimmer. The store no longer cuts diamonds on the premises. Many shoppers now find designs online and want the jewelers to help recreate them.

Ron Druker, the developer whose family has owned the jewelers building since the 1940s, says store vacancies are “a function of the changing dynamics of these once small, family-owned businesses — as the first- and second-generation owners succeeded, their children often went on to different professions.’’

Beth Healy

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