in no way a diamond expert but some of my friends are "prosumers"
do you have the full specs - L x W x D, crown height, pavilion depth?
the proportions are close to a 60/60 stone - you get more brilliance/ appearance of a larger stone but MAY sacrifice fire as well as scintillation.
I know for an engagement most guys here aim for high color (colourless - D/E/F) but in reality for stones <1 carat a good cut, under most lighting conditions, trumps all other "C"s.
One near-tai tai I vaguely know loves her rocks, and I replicate here her philosophy
1. Set a carat weight - which carat will you NOT go below?
2. Set a budget
3. Within the budget, look for the best cut. AGS0 is more stringent than GIA Ex. Do not settle for anything other than AGS or GIA. If GIA Ex - evaluate the proportions critically.
- H&A, being a subset of an ideally cut stone, is fantastic if you are into it. However, bear in mind that non-H&A stones can be as expertly cut and look equally spectacular. One usually pays a (highish) premium for H&A since retailers set the game.
- For romantic purposes, H&A are nice. But you will NOT see hearts & arrows in your diamond once set into a ring. H&A were a cute Japanese phenomenon that took off hugely (thanks in part to shrewd marketing).
4. Colour - some girls are more colour-sensitive than others, and can detect a faint yellow tinge where guys can't. Many H I J stones face up perfectly white - may only disclose a very faint yellow if viewed at an angle or if set beside a colourless stone. Some in fact prefer a warm white (HIJ) over icy white (DEF). In a (ring) setting, the superb light effects due to a good cut will supersede usual perception of colour.
5. VS2 and above, eye-clean SIs.
This way she maximises the carat weight for each purchase, while ensuring the stone performs well in most social situations - Big (carat) and Flashy (cut) - without overpaying for barely noticeable "C"s.
But in the end nothing beats sighting the stone - having it in your hand and turning it around.
IMO Singapore stones aren't the most competitively priced in the world, but I repeat I'm not an expert. Anything bought from a London jeweller's is equally eye-wateringly priced anyway.