As you probably know, authors tend to drink coffee. Here is a present I received from my daughter, Catriona. Four coffee cups like this:
I was slightly nonplussed when I opened the box. Yes, they are very lovely coffee cups. They are also rather black.
Until you add hot coffee. Then the black disappears to reveal the picture hidden beneath...
It's a Pericles Commission coffee cup! I now have a cup for each cover. Note the coffee within. My devious daughters and wife took the high-res bitmaps used for the covers to have these made.
Here is The Ionia Sanction cooling down. It reverts to black.
The entire family! Apparently I have to write more books if I want more coffee cups.
And the latest release, complete with cappuccino: