A Swiss jewelry brand whose sparkling pieces have been worn by several big-name stars — including Kendall Jenner, Rihanna and Ryan Reynolds — lies about using “ethical gold” and drags its feet on paying celebrities who promote the bling, a rep for the company says in a new Manhattan lawsuit.

Desiree Gallas, a public relations worker for Chopard jewelry, claims she persuaded A-listers — which have also included Uma Thurman and Nick Jonas — to rock the jewelry at red carpet events such as the Academy Awards and the Grammies, according to the lawsuit, filed in Manhattan Supreme Court.

The company tells well-heeled clients that its iced-out pieces are made from “responsible sources” with the “best environmental and social standards” — in order to “aide, artisanal small-scale miners and their communities,” the 37-year-old Bronxville resident says in the court papers.

But some of the jewelry was actually “secretly created by third-party vendors who did not use ethical gold,” Gallas claims — adding she repeatedly objected to the shady practices.

Along with the false advertising, she claims celebs such as Jenner, Reynolds and Thurman have recently soured on the bling brand because the company has a reputation for stiffing stars — or taking too long to pay them, according to the lawsuit.

The firm’s relationships with the stars have “dimmed due to Chopard’s failure to make / and or delay in making requisite payments to these celebrities,” the papers say.

And she says her bosses at the “dysfunctional” family-run company discriminated against her because she was American — with one honcho, Karin Scheufele, inexplicably calling her a “stupid zucchini,” according to the suit.

Other bosses implied “that she’s a trashy American.”

Gallas, who was hired in 2014, used her “influential contacts” to convince celebrities to wear the jewelry, according to court documents. She’s now seeking a trial by jury and an unspecified amount of money for emotional damages.

Reps for Jenner, Rihanna, Reynolds, Jonas and Thurman didn’t immediately return a request for comment.

A lawyer for Chopard called the claims “a waste of the court’s time and resources,” adding that Chopard was certified this year with the Responsible Jewelry Council.

“Chopard is disappointed that the Plaintiff has taken this path, particularly as the company is a highly regarded workplace with a global culture of inclusion,” said the lawyer, Jane Jacobs.