It’s a diamond in the ruff.

Cash-flush canine lovers can bestow their pups with ultra-luxe,18-karat gold and diamond custom collars — including one for a whopping $150,000 — thanks to a collaboration between the Baccarat Hotel New York and The D Diamonda self-proclaimed luxury jeweler for canine companions.

“There’s different tiers within jewelry. I would qualify this as fine jewelry,” one D Diamond client, Monica Bates, told The Post.

Every dog apparently does have its day — especially when rocking a six-figure bejeweled collar.

Bates was one of several prospective buyers at the recent showcase event, “Diamonds Are a Dog’s Best Friend,” held at the five-star Midtown hotel, located at 28 W. 53rd St.

A proud customer of The D Diamond, Bates previously lavished her miniature poodle, Harri, with a $1,200 silver chain — a small sum for the Canine Couture Diamond Experiencebilled as a “highly personalized luxury offering for discerning dog owners.”

For reference, The D Diamond’s Baccarat collection price tags can range anywhere from $1,984 — the starting price for the ruby-riddled Paw Deluxe harness charms — to upwards of $150,000 for the Heart Bone Collarwhich comes in yellow or white gold, and is elevated with D-color diamonds and other gems.

This iced-up chain is available by invitation only and for customers with a prior purchase history, evoking something that’d be gifted to a football star at a luxury lounge.

Prices vary based on the size — not all dogs’ necks are created equal, after all — in addition to the degree of customization and whether lab-grown or natural diamonds were used.

Each canine crown jewel also boasts several elements exclusive to Baccarat guests as well: The collars will be inset with a Signature Ruby, an ode to Baccarat’s iconic red crystal, and the tailor-made charms feature an exclusive “DD x Baccarat” design with rubies.

These include custom engravings with a dog’s name in case, say, you want to throw your dog a stone for, say, flying 15 hours first-class on pup-only airline BARK Air.

And, unlike with the Husky-owning hoi polloi, buying a Diamond Experience item doesn’t involve browsing the doggy jewelry in a window.

Keeping with the bespoke theme, human clients are treated to a private, in-suite consultation with the D Diamond boss — featuring Champagne courtesy of Baccarat — which helps ensure that the collar is a perfect style and fit for a fluffy ward.

“I believe that everything needs to be custom-made for a client,” D Diamond founder Racheli Waters Shamir told The Post.

The jewelry boss said the high-end concept was inspired by her search to acquire something “unique” for her dog, recalling, “I didn’t find anything, so I made one.”

Naturally, dropping six figures on dog baubles might seem paw-stentatious in a world where inflation-ravaged lovers are cobbling together a couple grand for lab-grown wedding stones.

However, Waters Shamir insisted that she wanted her brand to prioritize boutique craftsmanship and personalization over baller bling.

“From the beginning, I didn’t see The D Diamond New York as ‘pet jewelry,’ but as a fine jewelry house for canines,” Waters Shamir told the Los Angeles Times.

The D Diamond site also notes that the company donates 10% of its annual profits to canine shelters in New York City, adding a humanitarian dimension to this unabashedly opulent venture.

Plus, D Diamond representatives and customers alike insist their product is fit for humans as well.

[It’s] definitely for a dog, but also for yourself,” gushed Bates. “If I’m wearing it and getting compliments, it’s doing something.”

The Canine Couture Diamond Experience runs from now through June.