IN GENERAL - I prefer 6 claw settings.
This from my engagement ring tutorial:
Engagement rings - Claw Settings
Claws that hold diamonds are often made of platinum (even on yellow gold rings) because of its special features. With only 4 claws, you will show off more of the diamond, but 6 will hold the diamond more securely and are highly recommended for this reason.
The Tiffany style is a classic example of a claw setting, usually 4 or 6 claws on a half rounded band. This simple and basic ring is a great way to show off your rock, since it is lifted up away from the finger and is ‘floating’ in space.
Many people like to be able to see the side view of their diamond and it is commonly thought the open sides allow more light to reflect through the diamond. But if you have followed the tutorial about diamond cut quality then you will know better. Only light that entering the top of an ideal cut diamond can get back out the top. The light that goes in the back goes out the back.
Watch out for engagement ring settings that are wider at the base than the band, otherwise your wedding ring will not sit flush. However if the setting tapers too much the inside of the setting may touché the bottom of the diamond and dirt will get wedged in so that even a professional jewellers’ steam cleaner can’t dislodge it. This dirt kills the brilliance of even ideal cut diamonds. All our rings are designed to fit flush and make cleaning as easy as possible.
A final watchout - diamonds in exposed claw settings should have medium to thick girdles or edges to minimise the risk of chipping. Even though diamonds are very hard and very tough, they can chip or ‘cleave’ along this edge if given a sharp knock. This is one reason why you may choose to insure your ring, and remember too that if a claw is broken or worn off (especially in 4 claw settings) you could loose your diamond. An expert jeweller with gemmological training should check your ring for wear every year, and after a number of years, rebuild the tips of the claws.
hows that Alison?