My son is a nice kid, almost frighteningly well behaved. So it was easy, a few days before Christmas, to tease him after some minor offense - most likely farting - that Santa would start removing gifts he'd intended to leave. Robby, who still believes despite mounting evidence to the contrary, grinned, and said, "He'll start taking some away from you, too!"

At this point, I knew I had him. "Now how could he do that?" I said. "Who gives me gifts?"

He thought for a moment. "What do you mean?"

"Well, Robby, it's just that no one gives me Christmas gifts," I said.

This was not an effort to make him feel sorry for me. It is simply the truth. This year, my mother had my name in the family gift exchange. She gave me money some months back, in an effort to repay me for flying to Phoenix to pack up my sister's apartment. Friends give bottles of wine and small gifts, but on Christmas morning, there are no presents under the tree with my name on them. A light Christmas is the common plight, I think, of the single mom.

Each year, however, I hope, for that something unexpected. A gift of my own on Christmas Day.

Robby spent Christmas Eve and morning with his father, and arrived at my house Christmas night for our holiday. A fat stocking and a mound of gifts waited for him under the Christmas tree.

But before he dove into them, he handed me a tiny box, on which perched an equally tiny white bow.

"I got you something," he said.

I unwrapped the gift to reveal a small black box. The words "Fine Jewelry" were stamped upon it in gold letters. Inside, a small gold heart rested on a cushion of white foam. Trailing down its left side were seven small red-and-white stones. The chain was fine, almost spiderweb light.

"Why thank you, honey, that was so sweet," I said, and heard my voice emerge thick with emotion. My vision blurred with unshed tears. "I love it," I kissed him on the top of his head, touched my lips to his soft, blond hair.

"You're welcome," he said, and stepped away, pulling up his shirt. He pointed at his chest. I could count every rib on his thin frame. "See, it didn't cost me much. No stitches!"

I stared at him for a few seconds until it hit me. Robby was suggesting he'd sold his organs to pay for the delicate piece of jewelry.

We both laughed. He saw the unnatural shine in my eyes, then turned toward the tree.

I have worn the necklace just once so far, only because the clasp is so tiny it is nearly impossible to fasten behind my neck. This, I realize, is a clasp made for a child's hands, a necklace intended for someone more Robby's age than mine. He had chosen what he thought was the prettiest item in the store. And this thought, this picture of him carefully and proudly selecting his 11-year-old version of the very best for me, makes my heart ache every time it crosses my mind.

I plan to take the necklace in to a jewelry store early in the new year, and ask them for an equally fine chain with a bigger clasp. Because this is not an item that can sit, unworn, in my jewelry box. It should be worn as often as possible to show Robby how much I appreciate it, and to remind me - as though I could ever forget - how beautiful is his own little heart.