Jewelers craft customized spins on traditional diamond rings.

When a young couple approaches Kirkor Kocek about a diamond wedding or engagement ring, he becomes a teacher.

“I give them an education,” says Kocek, who’s crafted jewelry at his Carmel shop, Kocek Jeweler, since 1973. “I don’t try to make a sale.”

He starts with the client’s budget, he says, because there’s only a small profit margin in diamonds. Three key things to consider when picking out a stone: size, clarity and color.

It’s a sentiment echoed by other jewelers. “Clarity is the least important,” says Ramin Movahedi, managing partner at Carmel’s Pejmani of Belgium (whichWeekly readers voted best jewelry store in Monterey County in 2014). “Our eyes have the ability to detect the slightest differences in hue and size, but not clarity.”

Other factors to keep in mind: “Cut, polish and symmetry also impact the pricing,” Movahedi says. “And some colors are so rare, you’d be looking at something very expensive.”

For every 10 million diamonds, he adds, only one is a “fancy” color like blue, yellow, brown or pink. “The closer you are to the deepest colors, the better,” he says.

Gasper Spadaro, who opened Gasper’s Jewelers in Monterey back in 1972, says demand for colored diamonds rose after Ben Affleck gave Jennifer Lopez a $1.2 million pink diamond engagement ring in 2002. Lately, he says, the pendulum is swinging back to classic: “We’ve seen the trend go from colors back to white.”

One trend seems to be sticking: All three jewelers say it’s become increasingly rare for a man or woman to walk into a store alone to buy a ring for their partner. More often, couples are ring-shopping together.

When a client does come in alone, they get to play detective. “I [ask] to see a picture of his or her fiancee,” Kocek says. “That tells me the look of their design style and their lifestyle.”

Regardless of the budget, a ring’s style can be the hardest decision – and one that will have lasting consequences.

“We’ll show them all the designs we have in stock,” Spadaro says. “My favorite question is, ‘If you’re going to get married in an hour, which one would you want to wear the rest of your life?’