welltrainedmind.com states the Rules well. One must not:
"(1) Wear white on the bottom half of my person before Easter or after Labor Day; (2) Wear open-toed shoes before Easter or after Labor Day; (3) Wear linen or cotton voile before Easter or after Labor Day; or (4) Wear velvet before Thanksgiving or after Valentine's Day."
Somewhere in there is also a seasonal restriction on patent leather shoes. Of course, the exception to the rules was Resort Wear, if you were fortunate enough to be in Deauville for the season. To this day, I just can’t wear velvet in the summer. The very idea makes me perspire ... not just the heat and humidity, but the social embarrassment.
When Memorial Day had passed, Rich’s, The Store for Everything, stocked its jewelry counters with loads of cucumber-cool, chalky white jewelry: “ear bobs” of Haskell-esque wired-on white beads, necklaces of mixed chain and milk glass, white bangles to pile on the suntanned wrist. Just looking at them seemed to lower the temperature at least five degrees; they were cool to the touch and appropriate for the season.
Here’s a summer white treat for your neckline – a statement assemblage necklace of many elements gathered together to evoke those days when a lacy shirtwaist and the right accessories made you quite respectable, so long as you also had on clean, white shorty gloves.
The elements are an antique Dresden doll’s head of a boy in cap, a white enameled bow that was a lingerie pin in a former life, white beads from ear bobs, and a brass plaque from a fine furniture manufacturer, the well-known Maple & Co., which, with the antiqued, pale, syrupy Czech beads calls up the memory of maple ice cream. Oh, so cool and smooth!