#6. Lost Jewellery

#6. Lost Jewellery:

A couple went on holiday for three weeks. They carefully locked their house, and had a neighbour check on the place whilst they were gone. When they returned, the wife was distressed to learn that because of a power failure she had lost all her fine jewellery. She had hidden the jewellery in what she thought was a very safe place. She was not robbed. Her jewellery was lost by accident. Why?

Did you solve the riddle?!