Also, remember that the most important factor in the quality of a diamond is the QUALITY of the CUT.
i.e the ring in Newry may have the exact same cut(shape), colour, carat and clarity on paper as the ring on the web, BUT still vary hugely in quality.
What I mean is that a master diamond cutter can cut the diamond at the optimal angles (calle Ideal Cut), allowing the maximum amount of light to be reflected from the ring, making it appear more sparkly.
If the exact same stone was cut by a lesser stone-cutter, the ring could appear dull and lifeless, since the light entering the ring is being absorbed by the ring and reflected out the base or the sides, instead of the top (called shallow or deep cut).
A "Fine" cut is also satisfactory, but not as good as an "Ideal" cut.
To check out the QUALITY of the cut of the ring on the web, ask for all the measurements (e.g. ratio of Pavilion to Crown, size of Cutlet, ratio of table to diameter etc). Ask specifically for
- crown angle
- crown height
- pavillion angle
- pavillion depth
- cutlet
- table size
- girdle thickness
If it is a round stone, it is very easy to find on the web, the measurements to give optimal reflections.
Another factor is whether the stone has "Flourescence". This is a reaction between the light's energy and the diamonds atoms, causing the diamond to glow (perhaps slight blue colour). The jury is out as to whether this is a good or bad thing. Generally a lower quality diamond could benefit from some flourescence (more glow), but a higher quality diamond is better without flourescence.
I'd advise, get all the details from BOTH the shop in Newry and the web. And also if you buy a diamond in Amsterdam.
Best of luck - you'll be diamond experts by the time you've decided on the ring!!