Salt. It used to be common and white and came out of a shaker — unless it got damp and stuck.

Now it comes from all over the place, in different colors and sizes, and you sprinkle it on with the fingers, because these finishing or exotic or designer salts can cost an arm and a leg.

More than 100 distinct varieties can be bought online. Even a local Whole Foods stocks a dozen so-called sea salts, whose labels may or may not proclaim their place of origin. Then there are those that do, like the Maldon salt from England and the pink Himalayan salts that come in several crystal grades (and cost more per ounce than a pound of ordinary table salt).

In fact, a shopper could spend a half hour choosing a salt, especially if they read carefully. If there’s lots of salts, so too is there a profusion of company brands. Some claim their salt is “hand-harvested.” Some strive to overcome geography, claiming to be locally sourced even if it is Himalayan salt they’re selling.

“It’s amazing, the trend. It’s becoming much more mainstream,” says Peter Damiano, the Whole Foods “metro chef” whose territory includes Fairfield County, describing the market for finishing salts.

Damiano says he recently coordinated a pizza workshop where cooks used a finishing salt from the Cape May Sea Salt Co. (as in New Jersey) that paired well with the vegetable toppings. Meanwhile, he says he’s seen celebrity chefs showcase finishing salts and heard of 15 different salts being brought “to the table” for a steak house tasting dinner.

“It’s just like oysters; the flavor profile is based on the water they come from,” Damiano says.

For salts, this is doubly true, since all salts (the NaCl cooking kind) came from salt water at one time or another. Then, depending on where they are harvested, they acquire a distinct “terroir,” says David Kamen, of the Culinary Institute of America in nearby Hyde Park, N.Y.

Both a Himalayan pink salt and a Hawaiian volcanic salt can have a sulfurous taste, he says, while a Maldon can taste “flinty” or “limey” or even “dirty.” Except dirty can be good.

Kamen says one of the few salts he keeps at home is another coastal variety, Fleur-de-Sel gris. Its gris or gray coloring comes from minerals that leach down through pyramid mountains of drying salt.

“I like to use it on top of tomatoes in season,” says Kamen, adding that his “go to” salt for cooking is Diamond Crystal kosher, which is not exotic, but contains no anti-caking agent. Anything else would be a waste of salt and money, he says, and thereby hangs a tale.

Kamen, who was on the CIA faculty for many years and now works in its consulting department, is a sort of salt scientist, someone who’s thought about salt and even done experiments with it.

“The one that was really notable was the mashed potato experiment,” he says. “We divided a batch in half and used half kosher salt and half sea salt. I put it in front of people, and there was no perceptible difference in that matrix of potatoes and butter and milk.

“It’s the same with chicken broth. We used three different kinds of sea salt, and no one could statistically tell the difference. The other side of that is if you sprinkle something (a finishing salt) on top of sliced roast beef, your tongue is coming into direct contact with those crystals of different shapes and sizes. They tend to dissolve on your tongue at different rates and you get a different hit of saltiness and flavors.”

Kamen went on to explain the difference between the five basic tastes (of which saltiness is one) and flavor, which is “something that happens in your mouth and your nose,” while chewing and breathing.

The bottom line for cooking with salt, and what is taught in CIA classes, Kamen says, is that salt “is like the volume knob on the flavor that’s already there. So if you’ve got good flavor going, salt brings out that flavor. On the other hand, if you don’t have well-developed flavor, salt won’t do anything but make (a dish) salty.”

At the CIA, student chefs are not introduced to designer salts until they get to European cuisines. As with any herb or spice, Kamen says, so it is with a salt.

“You have to ask yourself what flavor am I trying to impart here. There’s no right or wrong answer.” There is a general rule Kamen says can be helpful: “If it grows together, it goes together.”

One more tip: “We typically season with our fingers. It gives us a little more feel, a little more control,” Kamen says, even when it is ordinary coarse kosher salt.

In any case, measuring salt by the teaspoon doesn’t make sense when the size of the crystals can vary so much. And the measuring problem carries over to diet.

“We get asked about those (designer salts) a lot,” says Larissa March, a clinical dietitian at New Milford Hospital and Griffin Hospital in Derby. “There’s pretty much the same amount of sodium in all salts, but the taste and the texture are different because of the extra minerals and larger granules.”

She worries that if people think there’s less sodium in a teaspoon of coarse designer salt, “They might take that as permission to use more,” instead of banking the savings toward the recommended daily amount, which is a measly 2,300 milligrams.

Some surveys have shown the average American consumes about 3,400 milligrams, but no one really knows because people eat out so much and use so much processed food.

As for health effects, March says, “There’s been a lot of studies. They can’t seem to come to any conclusion.”

The correlation between sodium intake and blood pressure is stronger than the correlation between lower blood pressure and lower risk of heart disease, she says.

March, however, offers one final fact. The chef at New Milford Hospital, which is known for its “plow-to-plate” program, uses kosher salt or sea salt in all recipes that call for table salt.

Joel Lang is an award-winning Connecticut journalist.