I only know that the sapphire tiara can also be worn as a necklace and some parts as pendants and perhaps brooches.
The tiara was already worn in the 80'ties so I doubt it could possible be a present from Mr. Weiler.
I recognized a few jewels from the auction but I have no idea of a jewel being a present of Mr. Weiler. It sounds quite logical that it would go to princess Sybilla.