They didn't use varnish. And there are fewer shadows. Theirs are more two-dimensional.
"I'm astounded, Your Majesty. But I believe this is the one by Isaac Oliver." Hawksworth pointed to the painting second from the right end.
"Let me see them again." Arangbar's voice was a husky slur. "I will tell if you have guessed correctly."
The board was handed up. Arangbar glanced at the paintings for only an instant. "You have guessed right, Ambassador Inglish. And I realize how you did it. The light from the candles."
"The portraits are identical, Your Majesty. I confess it."
"So we have won our point. And you won the wager, Inglish. Still, you won only because of my haste. Tomorrow you would not have known. Do you admit it?"
"I do, Your Majesty." Hawksworth bowed slightly.
"So, you did not really win the wager after all. We lost it. But I am a man of honor. We will release Nadir Sharif from his pledge. I am the one who must pay. What would you have? Perhaps a diamond?"
"The wager was only for a horse, Your Majesty." Hawksworth was stunned.
"No. That was the wager of Nadir Sharif. You have won a wager from a king. Yours must be the payment of a king. If not a jewel, then what would you have?"