Hi, everyone! Thank you for your responses.
Also, a HUGE thank-you to the moderators who removed the photos with my name and address. I was so upset that I didn't even notice that the address was visible -- my only thought was of showing the tear in the packaging. I was not logged in last night and didn't see the responses regarding the address label. A big thank-you to the community members looking out for me!
I was phoned by a manager at Tiffany & Co. today (appropriately named "Tiffany", by the way...) and she apologized several times.
She informed me that I am not liable for this lost parcel, as it was clearly the fault of UPS for leaving it on the doorstep. She stated that Tiffany & Co. normally requires a signature for items with a value of $1,000 or more, but that a parcel should not be left on a doorstep without ringing the bell regardless of the value. Apparently, UPS leaves dropping a parcel on a doorstep to the discretion of the driver, who is held responsible if a parcel is not received or is stolen before the intended recipient claims it. This is because all parcels - if left by the driver - are supposed to be left in a "SECURE" location not visible from the street or lawn, and that the driver is taking a risk in doing so.
Also, the representative I spoke to yesterday - Andrea - was a new seasonal employee and instructed me to forward my photographs to Tiffany & Co.'s customer service email address because she didn't know how to otherwise handle the situation. Tiffany informed me that, as a member of management, she will go over such procedures with Andrea to ensure that this doesn't happen again.
Tiffany & Co. will be shipping me a replacement parcel within 4-5 business days, this time with signature confirmation because I requested it. They will also be reaching out to UPS to claim the insured value of the item (as they are shipping a replacement) so my UPS driver will be contacting me to collect the damaged packaging I initially received.
Tiffany & Co. is correcting the problem and replacing my missing necklace. Yay! I have to wait a while longer than I'd expected, but at least I'll still be getting my necklace and I'm not out $630! A happy ending after all!
One thing, though... Can someone explain to me exactly why I feel so terrible that Andrea - the new seasonal employee who mis-handled my customer service call - is now in trouble with her managers? I feel guilty about potentially getting her fired... especially during the holidays... I even found myself apologizing to Tiffany for getting Andrea into trouble!!
Still, the lesson learned is:
1) To request signature confirmation on orders under $1,000 from Tiffany & Co., because it's not included..
2) To check UPS tracking information more frequently, as their shipping "estimates" aren't accurate and parcels arrive when they arrive..
3) To always ask to speak to a member of management, especially during the holidays when seasonal employees don't always know how to handle customer service claims..