I'm not any merchant's "man." Tiffany has a great name & reputation, but alternatives include Cartier, Harry Winston, and even Van Cleef & Arpels, and there are others.
My wedding rings were custom designed & made for me, with my input, by renowned independent jewelers I commissioned. And in my private photos I mention that my dinner jacket cuff links (barely visible in the smaller main pic with the iPhone), were custom made for me, as well.
I detest off-the-shelf jewelry, and almost always have my dressier formal things specially made and totally unique. Even my fountain pen was made for me.
Now there was a time I did favor certain stores, always in Manhattan, for particular needs. But some have gone out of business or evolved into something else. Many men's accessories are still available at Alfred Dunhill, though, where my father always got his smoking items, such as lighters, cigarette cases (an exquisite art deco one used to be my favorite as a kid), and later his pipes when he gave up cigarettes.
But my favorite leather goods store, Mark Cross, went out of business. I always got my leather gloves there, and some wallets, belts, and keycases when I favored those. In fact, I was at Mark Cross the very time of the Stonewall Riots, outfitting myself for the Army, oblivious to what was happening just blocks away. I got a lovely leather shaving kit there, which they generously engraved for me at no charge, when they learned how I would be using it. Not everyone hated our military in 1969.
I also got all my fishing & outdoor gear at Abercrombie & Fitch, when they were still a gentlemen's sporting goods store, before they became a twink clothing chain. My family had been going there for generations, and all our men were outfitted there for World War II, when it was possible to buy higher-quality replicas of ordinary GI-issue field items. One of my treasures was an Abercrombie pocket compass, that flipped open like a pocket watch, that my uncle carried when he was killed in France, the relative after whom I'm named. But Abercrombie's was getting run down in 1969, and my pre-induction visit there was a disappointment, buying nothing.
So I've had loyalties to certain stores, often following family traditions. But I'm not their "man."