Debra,
I have been using Cennini colors for some time now and the Naples Yellow is outstanding. The consistancy of these paints are perfect.
Over the years I've discovered that in addition to quality of paint the quality of the tube and cap system it comes in should be considered. Cennini has a good sturdy cap with a deep thread to keep the paints fresh.
These can be found at
http://studioproducts.com