quattro[Moderator]
18253
Patek Philippe's "manta ray" case
The case of Patek Philippe's ref. 2554, with its angular flared sides resembling the wings of a manta ray, hence its moniker, is one of the most sensuous I know.
It was the direct source of inspiration of the later ref. 5100, made to celebrate the year 2000.
Because of its thinner and subtler profile, I personally prefer the 1950 ref. 2554 to the modern ref. 5100.
Have a nice day!
A/ Ref. 2554 with caliber 9-90 1/ Rose gold

credit: fabsuisse vintage watch
2/ Yellow gold 

credit: ponti collection

credit: parthian watch company
3/ White gold

credit: phillips
4/ Platinum

credit: monaco legend auctions

credit: phillips
B/ Ref. 5100 Gondolo 10 Days Millenium Limited Edition with caliber 28-20/220
1/ Yellow gold ref. 5100J-001

credit: bonhams
2/ White gold ref. 5100G-001 
credit: s.song
3/ Platinum ref. 5100P-001

credit: @aleartuso.italy
4/ Rose gold ref. 5100R-001

credit: watch-out & patek-philippe.blogspot.hk