Call it a magnificent obsession: A 12-foot Christmas tree with 7,000 white lights and 600 ornaments.

But not just any ornaments: 600 Christopher Radko pieces, created by the king of designer Christmas ornaments. The tree’s creator, Ann Free, can name each and every one. She fell in love with them 25 years ago, and this kaleidoscope of glass, glitter and shine is the result.

And here’s the thing: You would never guess she’d adore this kitsch if you met her any other time of the year. Ann and her husband, Jim, a former Carter administration official and lobbyist, live in a sleek, elegantly neutral home in Kalorama. No curtain swags, no fussy antiques, no historic clutter.

“I’ve got a modern house that’s very unadorned and I collect nothing,” she says in her rapid-fire Southern accent. “I don’t have tchotchkes, and I grew up with tchotchkes. So I said, ‘What am I going to do?’”

What she did was scratch that itch with Radko ornaments. A lot of them. “Jim would say, ‘My whole damn net worth is in the basement.’ I spend a lot of time on eBay,” Ann says.

At yuletide, a corner of their living room is transformed into an explosion of brightly colored whimsy. Putting up this evergreen tree takes days and a small army of volunteers who painstakingly wire each ornament on the branches.

The final result is revealed at a holiday party where their guests spend an inordinate amount of time picking out their favorites: Say, the dancing monkeys. Or the complete “Wizard of Oz” collection. Or perhaps the “Trouble Trio” of blown-glass bad girls.

“It’s amazing,” says Tipper Gore, who attended the party and introduced the Frees to Radko ornaments. “Absolutely breathtaking. I bow to this tree.”

This is not your grandma’s Christmas tree. For one thing, your grandma probably couldn’t afford it: Over the years, Radko ornaments sold for an average of $50 each, but the rare ones now go for much more. His collectors are a passionate bunch, trading and buying and selling and competing to hang the most ornaments on one tree. (The record appears to be 1,200, but who’s counting?) Typing “Christopher Radko” into an eBay search yields more than 17,000 results.

However, this tree is inspired by a grandma — specifically, Radko’s grandmother. Legend has it that he caused her 14-foot tree to come crashing down, breaking hundreds of handblown heirloom ornaments collected over decades. His quest to replace them led him to a glass blower in Poland, where he commissioned some simple replacement ornaments for his family, and then to an empire.

Radko’s collection debuted in 1986 and became larger and more elaborate with each year. They were big, they were bold, they were fabulous — the drag queens of holiday decor. Then came snow globes and cookie jars and coffee-table books and collectors catalogues. During the 1990s, Radko creations were sold in the most expensive stores and adorned the chicest celebrity trees in America. He was the other Christmas star.

Radko decorated the Gores’ tree for their first Christmas in the Naval Observatory in 1993, and again for the next seven years they lived there. “There was such a unique vision for each individual ornament,” says Tipper. “It was different from the traditional Christmas tree ornaments.” He became friends with the second lady and created a custom piece of the vice president’s residence, and then became friends with her friends.

That’s how Ann — a self-proclaimed “Christmas nut” — got hooked.

It started small, as obsessions typically do. A Radko here, another there. The designer became a personal friend of the Frees, showing up at one of their Christmas parties dressed as an elf. Pretty soon they had a basement full of carefully packed storage containers filled with hundreds of favorite pieces. They gave Radko ornaments as gifts every year. Some of their friends now have their own mini-collection.

“They’re very collectible,” says Jim. “It’s like the stock market. And they’ve held their value very well.” Their personal collection is worth how much? Ballpark?

“Oh, honey.” He breaks into a laugh. “That means I don’t want to know.”

To be clear: Ann doesn’t own or desire every Radko ornament in existence. (The brand is still selling under his name, although he sold the company in 2005 and is now growing lavender in New York state.) She’s partial to the earlier issues and the Italian pieces, which she considers more delicate and whimsical than the other European-made ornaments. “The Italian ones are funnier,” she says, and her favorites are the ones that make her smile.

When she likes an ornament, she collects several versions of it. Hence dozens of “Russian Santas” all wearing slightly different coats. She’s sat in on some spirited late-night eBay auctions (there’s an original “12 Days of Christmas” set listed for $1,599), and there are still a few elusive pieces she’s dying to own.

“I want the ones I want — where I look and say, ‘I love this!” she explains. Her newest acquisition is a recent Beatles ornament: “It may or may not be collectible, but I love the Beatles, so it means a lot to me.” She can tell you the name of every ornament and has a relationship with each one. They are in her will, so they go to people who will appreciate them.

But it is not enough to own the ornaments or even place them on the tree in a conventional manner. After finding the perfect tree for her 12-foot ceiling, Ann gives it an extreme makeover: Branches are strategically chopped out, creating open sections to the trunk. More than 7,000 white lights are attached. The ornaments are carefully unwrapped from acid-free paper and bubble wrap and laid on temporary tables that cover the living room, dining room and entrance hall.

Then, and only then, are the ornaments placed on the tree: one at a time, with the metal ornament topper glued on and wire that is wrapped around each branch several times. They are layered throughout the tree, from the trunk to the branch tips, which has the layered effect of an elaborately choreographed Busby Berkeley Christmas extravaganza.

The end result is perfect, which is when she begins moving pieces around to make the tree imperfect. A perfect tree, she says, looks like something a designer might do. Ann wants this to be her tree. So “Mr. Holly Hopper” (an Italian dancing snowman) goes from the back left to the front right. Others are moved to higher branches because they look better from below. Switching things around can take all day.

Then it’s perfect.