By now, you should know that eyeballing a cup of sugar or teaspoon of baking soda does not cut it in baking. Even the slightest miscalculation can turn a fluffy chocolate cake into a dense sheet of sadness the moment it hits the counter. And while kitchen scales can help, pros like Christina Tosi like to take things a step further for maximum precision by using an ultra-accurate gem scale—a.k.a. the tool jewelers use to weigh precious gemstones. Because if it’s good enough for weighing rubies and sapphires, it’s good enough for weighing your kosher salt. Weigh Gram 200g Digital Pocket Gram Scale The two-time James Beard Award–winning chef and Milk Bar founder swung by the Bon Appétit Test Kitchen to show just how precise her Weigh Gram Jewelry Scale really is. It measures to the hundredth of a gram, which Tosi calls “diamonds-level weight.” To prove it, she measures out exactly one gram of salt on the gem scale, then places it on a standard kitchen scale, which doesn’t register a thing.…