She said she fired the piece at 1300 F for 30 min in order to give it the best strength and highest shrinkage. She chose not to fire it at 1650 F because sterling silver is an alloy of copper and silver, and copper has a lower melting point than pure silver. Her problem is that the sterling silver wire became weaker and broke easily.
I responded with this answer:
Firing sterling silver above 1200 degrees F makes the metal brittle and can actually cause it to crumble. The melting point for sterling silver is 1640 F / 893C. Maybe using a fine silver embedded jump ring or incorporating a hidden bail made from PMC3 clay would have worked better. This way, the piece could be fired at 1650 F for two hours.
Keep the questions coming! I hope to hear from you all soon! In the meantime have fun claying around.