Did you confirm that the diamonds are genuine? If the diamonds are in fact genuine, and the shank turned out not to be as represented, it's possible it was an accident/the ring was misslabeled, or the salesperson is inexperienced. I would go to an independent jeweler and get their take on the diamonds. If those are fake, then this looks like a stronger fraud case. In any event, you can ask them for a refund or write them a letter and gauge their response, as mentioned by the other attorney responses.
You also may have potential remedies under the California’s Consumers Legal Remedies Act (“CLRA”), Civil Code section 1750, et seq. This statute provides a cause of action for a seller's deceptive acts or practices undertaken in the sale of goods to consumers. See Cal. Civ. Code § 1770. For example, the following deceptive acts or practices are actionable under the CLRA:
(2) Misrepresenting the source, sponsorship, approval, or certification of goods or services.
. . .
(5) Representing that goods or services have sponsorship, approval, characteristics, ingredients, uses, benefits, or quantities which they do not have
. . .
(7) Representing that goods or services are of a particular standard, quality, or grade, or that goods are of a particular style or model, if they are of another.
. . .
(9) Advertising goods or services with intent not to sell them as advertised.
. . .
(16) Representing that the subject of a transaction has been supplied in accordance with a previous representation when it has not.
See Cal. Civ. Code §§ 1770, 1780. A consumer harmed by a seller that engaged in any of these proscribed practices may recover actual and punitive damages, as well as full attorneys’ fees and court costs. See Cal. Civ. Code ¬§§ 1780(a), (d).
My office regularly handles CLRA cases, and would be happy to give you a free case evaluation 510-981-0867.
DISCLAIMER: This reponse is for informational purposes only and cannot be treated as legal advice. Legal advice depends on the specific facts of the particular matter at issue. Accordingly, you should not rely on or act on any information provided herein without consulting with legal counsel that is licensed to practice law in your jurisdiction. This response does not create an attorney-client relationship between you and the Law Office of Arthur J. Obolsky.
You can send a demand letter. However, small claims court is the perfect place for you. Then, when it's over, you can tell the district attorney about the fraud. Make sure you take both the recieipt and the "analysis" of the ring as silver to court, one copy for you, one for the judge and one for the defendant, and proof of payment.
The above is general legal and business analysis. It is not "legal advise" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.
If you haven't already done so, get a professional appraisal of the ring. Then, you or your lawyer can send a letter to the store attaching the receipt for the ring, the appraisal showing that it's silver, and a demand for a full or partial refund (depending on whether you wish to keep the ring). If the store does not offer what you asked for in the demand letter, then you can easily file a small claims suit. The filing fee is only about $50 to $75 depending on how much you seek to recover and you can even file small claims lawsuits online. Good luck!