Check out the latest Signet Jewelers earnings call transcript.

What happened

Shares of Signet Jewelers (SIG -2.57%) were down 22.2% as of 11 a.m. EST Thursday after the diamond jewelry retailer announced disappointing holiday-season sales.

More specifically, in a press release this morning, Signet told investors same-store sales declined 1.3% year over year for the nine-week period ended Jan. 5, 2019. As such, Signet reduced its fourth-quarter guidance to call for a same-store-sales decline in the range of 1.6% to 2.5% (down from 1.5% to up 1% previously) and for adjusted earnings per share of $2.32 to $2.53 (down from $4.35 to $4.59).

Jeweler's tweezers holding a diamond.

IMAGE SOURCE: GETTY IMAGES.

So what

Today's plunge follows a nearly 40% decline in the month of December after Signet posted seemingly solid third-quarter results but offered narrowed full-fiscal-year guidance that left the market underwhelmed.

Signet also reduced that guidance today, calling for full-fiscal-year 2019 same-store sales to be flat (down from flat to up 1% previously), total sales of $6.24 billion to $6.26 billion (compared to $6.26 billion to $6.31 billion), and for adjusted earnings per share of $3.53 to $3.69 (down from its prior range of $4.15 to $4.40 per share).

Signet CEO Virginia Drosos admitted their results were below expectations, elaborating:

Early improvements in refreshed merchandise assortment, digital marketing and OmniChannel were more than offset by larger than expected declines in legacy product lines. In addition, the competitive promotional environment we saw early in the season intensified in December and, despite our increased promotional investments, we experienced reduced traffic during key December gifting weeks. Combined with higher than expected credit costs, these factors negatively impacted our profitability.

Now what

But Drosos also stressed that the company is planning to accelerate initiatives under its ongoing "Path to Brilliance" business transformation, which aims to improve its product assortment, marketing, promotions, services, and e-commerce solutions in the coming years. As it stands, investors will receive their next update to those ends when Signet announces final fourth-quarter results on March 14. But given this disappointing guidance in the meantime, it's no surprise to see the stock continuing to lose its luster.