Vintage AP Identification

[Pixiedust]

Hello, can anybody recognize this 1960´s, 1970´s piece? It has a very rare electric blue dial which is stunning. I can see there are other extra flat watches but this seems to be a rare piece which I cannot find any information on and difficult to value. Its got a white gold case numbered 42036 and a blue sapphire on the crown. Calibre 2003.

I have been reading in the archives as to say, and during this period Audemars Piguet created unique or special pieces within there production runs, often using different materials and colors, however identifying the watch is very difficult and hope someone can identify it and perhaps its value. There are more pictures if need be