Tiffany & Company had millions of dollars’ worth of shining, sparkling jewelry in its famous Fifth Avenue store on Sunday: $4,000 rings that spell the world “love” in small diamonds, $165,000 diamond necklaces, and even a $2.475 million engagement ring that weighs as much as a bullet.

Those things had to leave, along with hundreds of other rings, necklaces and brooches.

It was moving day.

Tiffany was emptying its 10-story fortress for a long-planned renovation. The merchandise had to travel only 50 feet or so — Tiffany will occupy a former Nike store during the makeover — but security was tight.

The jeweler assigned 30 security officers to watch as 114,179 “units of merchandise” — a “unit” being retailing jargon for one ring, necklace or brooch — were taken from their display cases and shuttled to the temporary store.

New York City police officers were standing by outside. They watched as the jewelry was rolled along the sidewalk in distinctive carts with robin’s egg-blue tambour doors. The color is so much a part of Tiffany’s identity that the company has a trademark on it.

But if the carts were somewhat showy, they were also meant to be secure. They had locks that were checked and rechecked, and before each cart was pushed onto the sidewalk, it was sealed in plastic shrink-wrap.

And Shifra Balancio, a Tiffany employee, was posted at the door of the store’s temporary home to keep a careful log of each cart that arrived.

There were 300 cameras monitoring the Tiffany store and about as many in the temporary store, as well as a few more trained on the route along the sidewalk, that were live feeding monitors surveilled by other security officials in the two stores and at Tiffany’s distribution center in Parsippany, N.J.

Employees had been told to keep word of the move quiet. That directive was repeated by Andrew Mikulskis, the Tiffany executive who coordinated the move and is overseeing the renovation, during a briefing for employees after the store closed on Sunday afternoon. He implored them not to post messages or photos on social media that might provide clues as to what was happening.

Well before that, Tiffany officials had monitored social media, looking for hints of potential criminality. Tiffany hired a company that tracks social media and provided a list of key words like “move,” “727 Fifth Avenue” — the address of the old store — “6 East 57th Street” and the move date.

As an extra security measure, Tiffany put up a tent in front of the door of the temporary store to block the view. Every item was entered into an inventory-control system when it was packed in the old store and checked off when it was unpacked in the temporary one.

The security was a reminder that over the years, Tiffany has had its share of headline-making robberies. Perhaps the most brazen took place in 1958, when two men sledgehammered the Fifth Avenue display windows in the middle of the night.

They broke the supposedly shatterproof glass and grabbed two diamond necklaces, a diamond pin and a diamond ring. Then they strolled to their car, waiting on Fifth Avenue, and drove away. The loot was never recovered.

Nothing was snatched on Sunday, according to Tiffany and the police. Tiffany said on Monday that all the jewelry from the move was safe and accounted for in its temporary quarters.

But on Sunday, the pressure was on. Employees said it was a challenge to move so much so fast.

Tiffany was determined to open for business in the temporary store on Monday morning. The company considered having a “down day” between when the old store closed and the temporary one opened, to have more time to pack, move and unpack. But officials decided to do it all in the 18 hours between when the old store closed on Sunday and the temporary one opened for the first time.

“They say moving is stressful,” Michael Vanderheyden, who has sold jewelry on the main floor for 35 years, said as the packing began, “and I’ve been anxious for the last two or three weeks.”

Employees appeared less concerned about the security — they handle expensive items every day without losing them — than with the process: scanning bar codes, packing boxes and loading carts. And, once the carts were on the way, workers had to learn their way around the temporary store, down to which drawer the ribbon would be in when they needed to wrap a little blue box.

But this is not Holly Golightly’s Tiffany. Last year Tiffany agreed to a $16.2 billion deal to be sold to the luxury giant LVMH Moët Hennessy Louis Vuitton. LVMH Moët Hennessy Louis Vuitton also owns Christian Dior, Fendi, Givenchy, Guerlain, Dom Pérignon and Bulgari (whose store is across from the one Tiffany is renovating).

Tiffany has worked to update its image in the last few years. In 2018, the rapper A$AP Ferg did a remix of “Moon River” with the actress Elle Fanning in a nod to “Breakfast at Tiffany’s.” And, ever since Tiffany opened a cafe in 2017, it has been possible to do what Holly Golightly did not — have breakfast inside the store.

The cafe did not make the move to the temporary quarters. Neither did another famous Tiffany item. The Tiffany diamond, a 128.54-carat dreadnought that Lady Gaga wore to the Academy Awards last year, was somewhere else. Exactly where, Tiffany would not say, except that it was in a vault in another location.

Tiffany is subleasing its temporary space from Nike. The building on East 57th Street is owned by the Trump Organization, which also owns Trump Tower, Tiffany’s neighbor on the Fifth Avenue side of its own building. Tiffany says that business slowed in 2016 after Donald J. Trump was elected president because security was tightened amid protests in the blocks around Trump Tower.

But Tiffany says business has rebounded since.

Tiffany moved into its building in 1940 after spending $2,484,079.09 on construction; as the writer Joseph Purtell noted in his book “The Tiffany Touch,” after several years of losses in the 1930s, “for the first time Tiffany’s was counting the pennies.” He wrote that the only items that disappeared in the move were “three inexpensive cups and two glasses.”

This time, Tiffany relied on employees who started emptying the display cases about an hour after the store closed at 4 p.m., two hours earlier than usual.

On the second floor, in what Tiffany calls the “love and engagement” department — where it sells engagement rings and wedding bands — Leslee Nugent, an employee, was packing a 10.64-carat engagement ring priced at $2.475 million.

She said it was the kind of ring that customers notice as they circle the display cases and ask her to take it out. “They don’t understand the gravity of it until I do,” she said. “That’s when they say, ‘How much?’ and ‘Oh, my gosh, how much is that again?’ They usually can’t believe it. They have to look at the tag.”

But it was not the only large ring that had to be packed up. Ms. Nugent said there were 18 rings in the same display case that weighed more than three carats, including an 8.41 carat ring (priced at $1.645 million) and a 4.52 carat ring ($779,000).

“There’s over $10 million in this box,” said Tony Mavashev, a salesman who was watching.

The box with the $10 million in rings was loaded onto a cart that was locked and, just before it was wheeled out of the employees’ entrance of the store, sealed in shrink-wrap. The police stopped pedestrians on 57th Street while it was in transit.

In the temporary store, the cart rode in an elevator to the third floor. Once the box was unloaded, Ms. Nugent carried it to a counter and began checking off the items inside.

She took the 10.64-carat ring out and slid it on her finger. She said it was a sales technique that had become a habit.

“I usually do this,” she said. “When a man is shopping for a ring, until he sees it on a hand, he doesn’t make a connection. He, or she, immediately envisions it on a partner’s hand.”