Regarding which GIA center, go beyond the academics years and see where you want to be in the future. Carlsbad is the MOST expensive place in terms of living expenses and facilities. Obviously, it is a seaside village, beautiful sunny pleasant but a vacation village and so expensive (public transport is terrible so you rent a car which is probably easier and cheaper in bigger towns, rent a room/ apartment/ paying guest expenses (which again is more than usual), food expenses (limited Indian stores so you cannot cook much though this you can work around by sharing and bla bla) and of course even the entertainment costs more because you will live in California. The rest of the expenses (if any) I think should be the same in all places.
If you are looking at GIA for future job opportunities, then decide where you want to spend your coming few years. Carlsbad is definitely not for foreign students looking for an H-1. LA is a great place too if you are looking at California as a whole. It is lesser expense. With the total expenses coming down to at least some 20K USD for the entire course (maybe more now since I graduated almost 4 yrs ago) you should think about how you can earn that amount back.
I’m sure that you are all from well-off backgrounds since you are contemplating GIA to begin with, but that doesn’t mean that you don’t want to earn back what you spend on parhai. If you do manage to secure a job right away it would pay a basic amount so do a bit more of ground work with all of that and make sure you know what you are getting into.
All that said and done, I am a GG from Carlsbad also did the Jewelry Business studies there. After graduating from Carlsbad and settling down in NJ, I recommend that you really need to know the job options available to Indians in NY, CA, Fl and where ever you want to go.
Carlsbad is for those who want to get into international trading at a high-end level. If you have an existing family owned business and want to join only for the knowledge, seriously, Mumbai is a great place to be in (minus the fact that you get to live in US :-) which I think is a great incentive since as a family of jewelers you will realize that this is the only break from family that you will get other than occasional vacations in the future)
If you want to get into international trading, then consider NY and LA centers since THAT is where trading really happens. If you are into colored stone trading then think about Bangkok. If you want a job in INDIA, think a dozen times before investing in your education abroad since it will take forever to earn it back in Rs leave alone making profits.
UK I shall not comment about, because though I have a lot of friends and business associates there, I have never even considered the place. The only reason why I would have ever gone to UK for the course over US may have been the fact that you can get work permit for certain no of hrs even as a student there and of course getting the VISA for UK is a piece of cake.
Here in the US you would get an Optional Practical Training towards the end of your course but it is not the easiest thing to do. OPT also means that as a student you cannot work on an M-1 Visa and you would have to stay an additional 3 months in basic salary and not really advance towards any particular career if you aim towards a business. You must try to call up alumni to find out their opinion.
As far as the quality of education is considered, there will be only a marginal difference if at all between the various centers. Most of what you absorb is absolutely dependent upon your own dedication and willingness to learn. If you are serious about getting the best out of GIA, then start now even before the term begins and start learning about what is available in the market where you want to be or where you are so that when you do study, you will know what to concentrate on.