Few times jewelers I deal with mailed me high value jewelry with UPS and they called me a day before to make sure I was at home to receive it. They say it's better to ship it to a business but home is fine as well as someone there to recieve it and the package is insured.
Of course the USPS will be less expensive and it's still insured but it may take longer to get there and their tracking information is not as detailed as the FedEx or UPS.
I have read some theft occurring at both Fedex and UPS depots so for my purposes, I have only been using USPS registered and yes, they do take longer, but I feel the security I get is worth the extra time.
Besides, if its good enough for the Hope diamond, its good enough for me :-).