Miss Manners is looking at the meaning of the gifts, not the cost – or the timing of the payments.

Dear Miss Manners: Several years ago, the sister-in-law of a dear friend passed away, leaving a large and very valuable estate. By clearing her houses before selling them, as the sole heirs of this woman, my friend and her husband ended up with a kind of treasure.

My friend quickly invited me to look at the many items they had kept from the estate. In the process, she gave me a beautiful coat, some unframed artwork that she said was “much more than me,” and a pretty gemstone necklace.

It was only recently that I decided to have this necklace appraised, and I was shocked to learn that it was worth nearly $30,000. Miss Manners, these friends are incredibly nice people, and I don’t question their generosity for a moment. Nevertheless, I find it hard to imagine that they would have given me such an object casually if they had known its value.

Should I tell them what I’ve learned, perhaps on the pretext of insuring the necklace rather than selling it? And, if so, how can I ask them without offending them if they would like the necklace returned?

They were quite rich even before this inheritance, and I am not at all. (I’m a retired teacher and my only car is out of steam.) But that’s not really ethically relevant, is it?

I’m sure my friend and her husband have long forgotten the necklace, and I’d like to sell it. Yet this dilemma keeps me awake at night.

The resale price of a gift is usually unrelated to etiquette – but not always. Nice young women do not accept expensive gifts from strange gentlemen, and, lest Miss Manners be accused of gender insensitivity, the reverse is always true as well.

Yours is another example: neither party understood the nature of the gift at the time it was given, which needs to be resolved. Tell your friend what you’ve learned and say you’re embarrassed because you couldn’t have accepted it if you had known its value – and that you really think you should give it back.

This will give your best friend a chance to tell you to keep it, which you can then do, with appropriate expressions of thanks. This approach is not without risk — you may have to go back — but no path guarantees both profit and a clear conscience.

New Miss Manners columns are published Monday to Saturday at washingtonpost.com/board. You can send questions to Miss Manners on her website, missmanners.com. You can also follow her @RealMissManners.