I also breed merles. I love their rare unique colours and markings. I do specialize in blue merles. In a litter you never know what you will get. Every pup will be different in colour and eye colour as well. Some will have beautiful blue eyes, brown eyes or some will the brown eyes with blue speckles in it.
They have a solid base colour (usually red/brown or black) with lighter blue/grey or reddish patches, which gives a mottled or uneven speckled effect.