Trying To Pull A Shady Deal

(I work at company that sells stone to go on houses. All of the stone is outside, and our location is surrounded by trees.)

Customer: “All of this is the same rock?”

Me: “Yes, ma’am. Everything in this row is the same material.”

Customer: “Why is this side so much darker?! You said it was the same!”

Me: “…ma’am, that side is in the shade.”