There are memorable Christmas gifts, and then there are really memorable gifts. Like, say, an engagement ring.

According to wedding experts and social media sites, Christmas Eve and Christmas Day are the most popular days of the year to pop the question, followed by New Year's Eve and New Year's Day. (Yes, Valentine's Day proposals are still a thing, but they're proving less popular these days.)

"It's a special, emotional time," says Matthew Rosenheim, president of the Tiny Jewel Box in Washington, D.C. "People are around family, and they want to share those special moments when there's time to enjoy it without some of the pressures of day-to-day life."

The Knot, the online brand that celebrates all things engagement and wedding with unbridled enthusiasm, has a "How He Asked" website specifically dedicated to proposals — and five pages devoted just to holiday engagements.

There's a Rockefeller Center Tree proposal, the ice skating rink proposal, the tree farm proposal, several "Will you marry me?" in Christmas lights proposals, all recorded by a photographer or videographer hiding in the bushes. There's even one that doubled down on the "Awww" factor: A surprise French bulldog puppy under the tree, with a "Will you marry me?" tag hanging from its collar.

All of this requires military-style planning, especially during what is now known as "engagement season."

"We definitely see a spike in December," says Dino Pampillonia, co-owner of Pampillonia Jewelers in D.C. "Generally, it's couples who come in. But during the holiday season, it's guys wanting to do a surprise."

Most, he says, tell him they plan to propose by Christmas, although it can be a few days before or afterward.

What's important, his customers say, is that "all the families are together, and they want it as a family event."

Unlike the movies, most people do not walk into a jewelry store and walk out that day with an engagement ring — most buyers take four to six weeks. The annual parade of single men wandering into jewelry stores begins in November, many with only a vague idea of what kind of ring to buy.

"They have done some research and they've asked some questions," says Pampillonia.

Some, however, decide at the very last minute on a surprise proposal. Every year, the Tiny Jewel Box gets at least one customer who walks in and is willing to pay big bucks — but has to pick up the ring by Christmas Eve.

According to the Knot's Real Weddings Survey, the average cost of an engagement ring in the United States is just over $6,000, but can be less or much, much more. Rosenheim just sold a seven-carat, cushion-cut diamond ring for $350,000. (The proposal already happened and, yes, she said yes.)

There is some debate among etiquette experts about whether an engagement ring counts as a Christmas present, or if another present should be under the tree. Depends on the couple and the circumstances, most agree.

Legal considerations

But there's another, less romantic consideration for slipping another gift under the tree: the legal issue.

Although December is the biggest month for engagement ring sales, legal experts (those unsentimental pragmatists who find the downside in everything) warn that holiday proposals have a built-in risk.

Legally, an engagement ring is considered a "conditional gift" based on the marriage taking place and the ring goes back to the purchaser if the engagement is broken, regardless of who ends it. But rings given on Christmas, Valentine's Day or birthdays are typically classified as more traditional gifts, and the majority of courts allowed the receiver to keep it.

No one ever talks about that in a Hallmark Christmas movie.

When expectations are high and everyone else is posting engagement photos on Facebook, Rosenheim has this small piece of advice to longtime boyfriends shopping for a Christmas present: "If you're not going to give her an engagement ring she might be anticipating, no ring-size boxes for you. Don't pull out a square box if it's not what she really wants."

And every jeweler sees some of those men in January.

"It's like clockwork," says Rosenheim. "You can tell by the expression on their faces. Their significant others were anticipating a Christmas engagement or a New Year's Eve engagement, and the next big thing is Valentine's Day. We all know we're going to see those customers who say, 'Yeah, I should have done it. I didn't. And here I am now.' "