And Then There Were Three

Scallop 10"x10"

Nautilus Interior, Scallop, Whelk, 10"x10"

The Rogers Gallery has held the Nautilus and Whelk paintings for about a year.  Nautilua Exterior had been a part of the trio but was sold separately.  Now, a client wants a new painting added to create a series of three.  He is open to the shell and only asks that the colors be the same.  

The top image is a work in progress. The difficulty is in incorporating the colors from the other sheets without creating an artificial appearing shell.  This stage needs more blue. But, how?