The Smithsonian Institution's diamond collection includes the 45.52-ct. blue Hope diamond and the 30.62-ct. Smithsonian blue heart-shape diamond. Its recent exhibit, "The Splendor of Diamonds," included the 27.64-ct. Steinmetz blue heart-shape diamond, which meant that the Smithsonian was temporarily in possession of three extremely large, extremely rare, and extremely valuable fancy deep-blue diamonds. It was the perfect blue storm of a photo opportunity. But first, the Hope and the Blue Heart had to be removed from their mountings. And afterward, they had to be reset in time for the next morning's museumgoers. Jeffrey Post, curator for the gem and mineral hall, called his local jeweler for the job. "It was a real pleasure to do this," says Stephen Clarke, goldsmith for Liljenquist & Beckstead Jewelers in McLean, Va. Clarke, who also set the Steinmetz pink in its temporary pen