The first normal standard clarity grading recognised the world over was introduced by the GIA in America at the end of the 1920s. Also the 10 times loupe was also recognised as the magnification used to grade diamonds. This was needed to be able to recognise diamonds and sell diamonds by description and make it easier to trade.
Inclusions have 3 different phases of growth.
In America a Flawless diamond is a diamond that is flawless internally and externally any negligible features that could easily be removed by polishing are ignored. So they have 2 grades F flawless and IF internally flawless.
In Europe F flawless is only graded on the internal properties of the stone. So a diamond in Europe that is internally flawless is classed as F flawless.
All these grades are graded by looking in the diamond from different angles. But the final grading is done looking straight down on the table and it is the look of each inclusion at this angle that decides the grade. You could have exactly the same mark in 2 diamonds and if 1 mark was in the centre of the table and in the other diamond the same mark was on the outside of the stone they would be 1 grade apart.
Also say a fracture or cleavage mark was the same size in 2 diamonds and you could see the whole mark while looking into the table in 1 diamond and in the other diamond you could only see the side of the mark these would be 2 different grades.
It is not that easy the grades depend on the size the position the amount the colour and type of inclusions. You cannot possibly look at a small picture and be able to know the grade. If you look through a 10 times loupe not a 3 times or any other. (This will be marked on the loupe 10 times). You will not be able to see a vvs inclusion and you would see a vs inclusion but you will have to look properly. It is not that easy to use a 10 times loupe to start with. A si inclusion would be relatively easy to see in the stone and can be a small black mark or slightly larger white mark or feather/crack. You must remember you are looking through a 10 times loupe and the size of a SI inclusion can look quite large through this. Take the loupe away and see if you can see the inclusion with your naked eye if you cannot it is a SI stone.
The size and position of all marks is relative to the stone and relative to whether you can see the mark by eye without the loupe.
Grading diamonds is very hard it is not something that can be easily learnt if you know someone you confident with use him or her. If you are not sure get an expert. I have a lot of stones I would not sell these days bought when I first started. (These are still better than the high street quality but I only sell the very best diamonds now.) These will go to auction and I will get my money back because even then I knew a bit more than most people. I did not buy wrongly but if you are buying 1 stone use someone that knows and will guarantee his or her choice it is not worth the risk not to.
You may think you are getting a lot more for your money but 99% of the time you are not. My job and my passion are diamonds and I have got it wrong in the past. Every day we all learn more but unfortunately it costs money learning.
I will now list the types of internal flaws that can be seen.
If you would like to know more or you have seen a diamond that you have a close up picture of and you would like me to look at please e mail me and I will be happy to do so. (Please do not e-mail the picture in the first instance). The easiest thing is if someone has told you a diamond is a certain type ask him or her to send it of to an independent lab and have it certificated. Tell them you are quite happy to pay the extra cost if not don't buy the stone.
If you would like to know more I am writing a book. At present and it should be ready in a few years you can reserve a copy or if you have a specific question please e-mail me. I will try to reply as soon as I am able. Normally on a weekend as I am very busy during the week.
Thank you for your time and I hope you will choose wisely.