Voracrious Violinist:
Having looked at Goldsmiths Diamond Rings online they are not good value at all.
6000GBP for a 1ct I colour I1 clarity brilliant is a rip off. It does not even tell you what the Cut is. They sell another one for 8100GBP and it simply states the setting is in Platinum, nothing else.

Basically I colour is quite low down the colour scale and not considered White.
I1 Clarity means there are inclusions visible to the naked eye. This combines to create a rather poor stone.

In all honesty I would avoid Goldsmiths like the plague. You can without much effort buy a 1ct I colour SI2 clarity stone (The grade above I) for 2000GBP, in the UK.

www.bluenile.co.uk / com is well known online Diamond and Jewelry store with good prices for being in the UK. The Solitaire settings are not stunning so I would recommend getting the rock there and then go to a respected Jeweler and create your setting. With a nice stone for half the price of Goldsmiths.

Alternatively head over to Cooldiamonds.com as recommended by Raffles where you could buy a 1ct H Colour, SI1 Clarity, Premium Cut set in Selena Ring (classic Tiffanys style, thinner towards the Diamond) for 3447GBP. This is not a bad Diamond Ring. It is not stunning, but to most people it will look the goods.

Please ask if you require more assistance.