Important: One thing to note up front here is that not all images actually have any areas in them that are supposed to be neutral gray, and obviously, you can't find what's not there, so if that's the case with your photo, no technique for finding midtone gray will work.
Unfortunately this colour is much more true to blue than green. I now have a soft turquoise but washed the colour out after only 10 minutes. So I'll be surprised if it lasts for more than 2 weeks. Overall I think the Joico colour has great pigment but don't go with the colours you see on the package!!
Art application varies and includes painting, metal and mica overlay, lamination, riveting, color tinting, and torch fired plique a jour enamel. All custom work is made to order. Some of the shades pictured here are very complicated and take over 40 hours to make.