In answer to your question, mike. The yellow fades slightly but remains yellow until it drops off.
As my own seedlings started to flower I started to give away the pink ones, only keeping the ones with better caudex and more or different flowers flowers . Then I started to learn grafting and realized I was giving away all my rootstock so that has stopped and I keep everything.
My plans, as my own, grown from seed plants, start to flower is to keep all the good specimen plants and probably sell the surplus ones for two reasons.
1. to make room for more keepers and 2. to recover a bit of the considerable money this hobby costs us.
Here are a couple more of my pictures.
This was a plant called GEM at first flowering in April 2011. As it was when I purchased it
This is the same plant at it's second flowering just recently. As I bought it from my friend at the markets I have promised to give her a graft from it.
The only plants of my own growing I have had flower to date have bee all pinks from the first 61 seedlings my daughter gave me. The only other one was supposed to be a Vietnamese Purple from some seeds from a supplier in Aust. It was not purple but had a reasonably nice flower anyway
This is my other yellow. It loses a bit more colour than the lemon one
Cheers