Ok...here is 'Endless Questions' number 952 (approx!)

How to see lifting of product when using coloured or opaque gel?

(short and sweet question for a change!)

Hi, when opaque gel lifts from the natural nail, it's a slightly lighter shade at the lift than the gel that is still adhered to the natural nail. Believe me, you can tell it's lifting...

I'm not sure about darker colored gels, tho... HTH's.

I had a client in for infills for Calgel - they were done by my colleague. I cant remeber which number gel it was - dark sparkly red, and they looked gorgeous still. When i started to buff down the gel the whole overlay just started coming away. It was half lifted off the nail plate on a few nails (she never remembers top coat and never wears gloves etc...) You couldn't tell at all by looking.