Unless otherwise stated the diamonds used in the gold work, are GHSI1 quality. GH refers to the colour, with our diamonds sitting between G and H on the colour scale (of D-Z) and therefore considered very good. While SI1 refers to the clarity, with SI-1 indicating any flaws are not detectable during normal wear.
For a visual of what this means, and to help you make a discerned choice, we really like this visual guide on jewelry designs website.