Green’s Dictionary of Slang

fender n.

a tiara.

1885		C.H. Aïdé Introduced to Society 153: Isn’t Lady Davenport’s tiara magnificent? Mr. Davenport calls it, ‘the family fender’ — isn’t that wicked?
1893		M. Cholmondeley Diana Tempest in Temple Bar 98 197: Presently she moved away with Lord Frederick in the direction of Madeleine, who had installed herself at the further end of the room among the fenders, as our latter-day youth gracefully designates the tiaras of the chaperones.
1894		E.H. Dixon Story of a Modern Woman (2004) 121: [...] the sunlight sparkling on the diamond tiara round her forehead. ‘She’s got her best “fender” on [...] By Jove, did you ever see such jewels?’.
1902		E. Glyn Seventh Commandment 52: I flung it into the little china tray, where strings of pearls and a fender tiara are already reposing.
1913		E.T. Fowler Her Ladyship’s Conscience 215: ‘Eleanor always says that when she puts on the Mershire diamonds she feels the respected shades of her ancestors-in-law closing around her,’ said Esther, still smiling; ‘and that with a diamond fender on her head and a diamond poultice on her chest a woman can face anything’.
1921		E.F. Benson Dodo Wonders 85: ‘I will wear what Jack calls the family fender,’ said Dodo. ‘Tiara, you know, so tall that you couldn’t fall into the fire if you put it on the hearthrug.’.
1931		J. Tey Expensive Halo 163: The opera is the only place in London nowadays where you can wear a diamond fender without looking a fool.