Congrats to you both.

It sounds like size is important but you really do need to check colour and clarity also. I'm sure Mrs Highlife will be just as concerned with these.

The certificate will show you these details . You need to bear in mind that a large diamond can be a fraction of the price of a decent diamond half its size. I have seen some shocking quality large diamonds that people have got for "bargain prices". You cannot compare on size alone.

Colours run from D (brightest white) to Z (horrible yellow).
They can be subdivided
D, E, F Colourless
G, H, I J Near Colourless
K, L, M Faint Yellow
N, O, P, R Very Light Yellow
S to Z Dark Yellow


Clarity runs from
F Flawless
IF Internally Flawless
VVSI Very Very Small Inclusions
VSI Very Small Inclusions
SI Small Inclusions
LI1 Large Inclusions


I would go for colour and clarity and cut over size any day. If you can find all 4 then great. She will be one very happy Mrs Highlife.

Also bear in mind that white gold is relatively cheap and will probably need replating over time especially if to be worn next to a wedding ring. (See http://www.18carat.co.uk/whitegoldturnsyellow.html for details) I think platinum is a better bet and harder wearing although more expensive initially.

I would reccomend South Africa or Mauritius as best value. Choose the individual stone and setting yourself. Normally made within a couple of days.