“I solemnly and sadly open the debate on the impeachment of the president of the United States.”

So said Nancy Pelosi, the speaker of the House, on Wednesday morning as she stood in the cavernous chamber of the House of Representatives in a lapelless black suit, almost military in design, with a high neck. Its somber color was a reflection of the darkness of the day and the conscious choice for a woman fluent in the communicative uses of color. Atop it, a dagger-like gold pin shone out over her heart like a beacon.

But what was it?

Immediately the watching public began to wonder. After all, it was impossible to miss, standing out not just against her suit, but amid the sea of little congressional buttons and American flags worn by Ms. Pelosi’s colleagues. (In politics, a pin is never just a pin — at least not since Madeleine Albright published a book on her brooch diplomacy.) Clearly it was no mere decoration.

Indeed not. It is her power pin.

Literally (and also possibly metaphorically), it is a symbol of the office she holds.

And though there was some confusion in the watching public over what, exactly, it was, with some speculating on social media that it represented the Caduceus pin, or a medical symbol, and others comparing it to the Hand of the King from “Game of Thrones,” the pin actually represents the Mace of the United States House of Representatives: the long, blunt battle staff that has embodied the legislative branch’s authority since 1789.

Take that, ye errant executive, or something.

According to a website that catalogs the history of the House of Representatives, the mace is composed of 13 bundled rods, which look like a dagger from afar. They nod to the ancient Roman fasces, used to communicate strength through unity, and represent the original 13 states. The bundled rods are crowned by a globe — i.e., the world — atop which sits an American bald eagle, representing the obvious.

The object itself, the site says, “is usually placed atop a pedestal to the Speaker’s right side” when the House is in session. If the House meets outside its traditional chamber, the mace follows.

The current House mace was made by the New York silversmith William Adams in 1841, but Ms. Pelosi’s pin is a somewhat more modern interpretation.

It was made by Ann Hand, a designer in Washington, D.C. who specializes in patriotic jewelry, and is the wife of Lloyd Hand, the chief of protocol under Lyndon Johnson. According to her website, Ms. Hand is also responsible for “the official pin worn by the spouses of the U.S. House of Representatives” and has also made “brooches for all the Armed Services, the Naval Academy and West Point” (among other governmental bodies).

Her mace pin is brass with a gold overlay and has a pearl (or faux pearl) for the globe. It sells for $125, and at the moment it is on backorder. Its most famous owner has, apparently, set off something of a trend.

This is not, after all, the first time Ms. Pelosi has worn her pin. Indeed, she has worn it on a number of important public occasions since first winning re-election as speaker of the House.

She wore it, for example, at the president’s first State of Union, on the lapel of her cream suit, when she and many of the women of her caucus wore white.

She wore it in June, atop a royal blue jacket, during an interview after the president had called her “vindictive” and a “disgrace” in a post-D-Day interview with Fox News.

And she wore it in October, on a sky blue jacket, when she and Representative Adam Schiff held a news conference to announce that they had decided to move forward with articles of impeachment.

It is, in other words, a symbol, made of symbols, being used as a symbol.

And it tends to make its appearance in situations that merit an implicit reminder of what exactly it is the House has been empowered to do, and whence it derives its authority. Like, for example, the kind of situation described in the Constitution, but which the president has labeled (in his recent letter to Ms. Pelosi) “invalid” and “illegal.” Which is to say, the current impeachment vote.

In such a situation, as Secretary Albright might have said, all the watching public has to do — whether Ms. Pelosi is speaking or not — is “read her pins.”