These days, you can buy Christmas tree ornaments that “match” one another. They come in sets themed by topic (cooking, African animals, gardens), or color (cream, blue, gold), or even texture (feathers, twigs, burlap). And maybe one day these will be heirloom ornaments. But it’s going to take years and years of hanging, storing, unpacking, and claiming, “This is my favorite ornament!” for that to occur.

Heirloom ornaments are probably, properly, thought of as those fragile old globes or ovals that sometimes feature pearls, glitter, and etching. But not always. Look at your ornament box. An heirloom ornament is the one you dig for first, to hang in some prominent place on the tree. My heirloom ornament is a tiny manger scene. Mary and Joseph are barely more than plastic blobs, and the sheep has lost whatever paint it once bore, but the ornament was a gift for being in the Junior Choir at my church, and for me, it’s Christmas. Yes, I have a Steuben glass ball that’s probably worth a lot, and a dozen sterling silver Reed & Barton beauties, but this palm-size trinket, a humble shed, trumps them all in value.

Look at the box again. Among the usual holiday symbols — snowmen, teddy bears, rocking horses, and Santas — are the categories and echelons of heirlooms.

Here are the Personalized. Not “personal” — an heirloom is by nature personal — but actually personalized. The ones with names or initials painted on or glue-gunned to their surfaces.

Here are the Lifestyle heirlooms: the rainbow trout. The martini glass complete with olive.

Here are the Commemorative heirlooms: a vanilla-colored computer marks my first foray into writing. A pair of tiny clogs recalls a trip to Amsterdam for my mother’s 70th birthday. And that’s no reindeer; that’s a moose, for the family trip to Yellowstone. A replica of the Market House in Fayetteville, because it was precious to my preservation-loving mother-in-law. A Moravian beeswax candle wearing a frilly red collar and tucked into a circle of tin, from a friend of 40-plus years who lives in Winston-Salem. A banana, because my father, dead for nearly as long, so loved them.

You don’t become an heirloom simply by being fragile, or old, or expensive. Like the Velveteen Rabbit, you have to be beloved as well. Which is why we keep the Homemades. The wee stocking a friend knitted on tiny needles. The crocheted snowflake, from the cousin who’s into crafts. Our children’s handiwork from school or scouts: the God’s eyes created with Popsicle sticks and yarn; the golden Mason jar lid band framing a school picture; the construction paper wreath with macaroni ornaments.

Until the final heirloom is lifted, reverently, from the collection: the star for the treetop, or, in our house, the angel. She’s holding a banner that says PEACE, and is wearing a flowing, peach-colored robe. What can I tell you? Peach was very big in the ’80s.

And that’s how Christmas ornaments become tangible timelines of our lives. Few people set out to designate an ornament as an heirloom. That ball, or star, or angel, or banana, becomes one. It evolves into an irreplaceable treasure. Often, it has simply survived: survived breakage, survived trends, survived being loved to, well, pieces. Whatever decoration touches your heart, stirs your sentiment, triggers your memory, makes your inner child smile — that’s an heirloom.

Careful now. Not too high. Somewhere your eye will always catch it.

There. Perfect.