But that was my point, Mustafa...'jade' in this saying comes from the knackered old horse/nasty old woman version and not from the mineral version of the word. Consider the two words' histories...
"Be blithe though thou ride upon a jade" appears in Chaucer's Canterbury Tales from 1387...clearly, an inferior horse.
"Such a jade she is and curst a quean
She would out-scold the devil's dame, I ween."
This appeared in a poem dated 1560. Fortune, error, nature, poverty etc were also all called 'a jade' by one writer or another. Clearly, in the two centuries since Chaucer, the word had become attached to a wicked, mischievous, conniving woman.
'Rumour' is just another example. In exactly the same way as "old wives' tales" were not to be trusted or believed, nor were rumours spread by nasty old women.
'Jade', the mineral, did not appear until later in English and 'jade', the colour, not until the 1920s!
But what the hey! I'll leave it at that. Cheers