Judith Martin: 'This is not just a wedding picture (taken days earlier in a studio – I looked a lot happier at the wedding) but an etiquette crisis. My grandmother had firmly implanted in me the rule that a lady wears only odd numbers of strands of pearls: one, three, five on up, if she is lucky, to a choker of 11, 15 – whatever she can fit on her neck and still be able to swallow her dinner. I must have been just as firm in passing this on to my daughter, because once, in a sentimental mood, I asked what she had learned from me all her life. "Only wear odd numbers of strands of pearls."