Well, you only need the light when it's burning low.

Sesshomaru got home late, and the lights were not working, so he lit a candle and went looking for his mate. He walked into their room, and his heart about flew out of his chest.

There on his pillow was a pink small jewel.

His mate was mortal. The jewel was dull, but his eyes turned bright red with emotion that no one was there to see.