No one would ever mistake Zales for Tiffany.

Zales started out in the Texas oil patch, in the 1920s, with one jewelry store and a tempting pitch: go ahead, America, buy your bijoux on credit. “A penny down and a dollar a week” -- that was the line.

Today Zales’s parent, Signet Jewelers Ltd., is taking that old idea to unusual heights. Some analysts say Signet is pushing the limits of credit and accounting so far that it’s starting to look less like a jewelry business and more like a finance company -- a sort of Money Store for diamonds and baubles.

The approach has helped make Signet one of the world’s largest jewelry companies. But behind its sparkly empire lie consumer loans that bankers might consider subprime debt.

Just how Signet sizes up its customers and accounts for its loans has some investment analysts pressing for more information. Last year, the company generated nearly one-quarter of its $381.3 million in profit by financing, a calculation Signet says doesn’t give a full picture. Most retail chains, by contrast, farm out that part of the business.

“There is a risk here,” says Ufuk Boydak, managing director of German fund manager Loys AG, who calls the company well run even though his firm trimmed its Signet position in 2014 and keeps a close eye on its payments. “The credit business can get complicated. If things were to turn negatively, you have the recipe for a potential disaster.”

Sound Approach

Signet, which is domiciled in Bermuda and headquartered in Akron, Ohio, says its approach is sound and crucial to its success. It points to years of managing loans without outsized losses, which it attributes to robust credit standards.

Despite a brisk 2015 holiday sales season at Signet, bolstered by sales of its Ever Us diamond, some stock-market investors are pulling back. After five years of heady gains, the company’s stock price has started to wobble, falling 37 percent as of February 11 since reaching a record high of $150.94 in October to $94.71. The S&P 500 has declined 12 percent in that time, while the S&P Retail Select index is down 16 percent. Short bets against the stock are now running at their highest level since February 2013.

The developments are the latest turn in the long-running story that is Signet. It started in the 1940s in Britain, as Ratners Group, which stunned the country’s staid jewelry industry by offering cut-price deals.