Hi MD.   I am not sure about the exponentially part.  They do go up once over a carat...David can tell you more about the colored diamonds.  As far as replacing a stone goes...I would just buy a whole new ring from David.  Trust me...by the time you pay someone to reset the thing (and lordy knows how it would look) you can just get a whole new one at what is much less than retail.   I have never seen colored diamonds at better prices (from someone that I trust.)  If David says it then it is true and by true, I mean the GIA would agree.  Plus this site is about getting two rings for the price of one...no one here is going to pressure you to consolidate!!! 

Hi AZ thank you!  I was looking at the sparklies and OMG so beautiful.  I saw that ring too, it's gorgeous!   The pendant I have inspired me to get a matching ring too

hi!  it's nice to see another New Yorker in the house!!!  Welcome and don't be picture shy!

Nope AZ all diamonds I can post it here, it's also posted in the gallery:

Hi Sanchica, thanks!  I posted a pic of my pendant, pics of my ring to follow when I get it right now the center of the ring is a peridot, but I plan to change it in the future.

Hello and welcome!

So envious that you live in NYC and can just take a stroll throught the diamond district! I have to endure a 6 hour flight to be able to do that (after an hour and 20 minutes, DH will start the incessant "are we nearly there yet?" too!)

Nice to see you here, looking forward to seeing your peridot!

Jen

Welcome!  Cool pendant.  Reminds me of the one DJ had redone recently.  Cannot wait to see your ring. 

As for the size of the center to use when you get a diamond, I think that will be dictated by the setting, since you already have it, no?  The new center will have to fit in. 

Welcome MissD! What a beautiful pendant!  I can attest that this is the place to be for "help" with your addiction.  I'm looking forward to my second purchase from David in 4 months. (I will stop now...I will stop now...)   

That pendant is amazing!!!  I am all about paying a little a getting a "Big" look from it.   

Thanks Ronda!  I really adore the pendant.  Actually I added the diamond circle because DH bought it for me so I figured I could wear both!  I've seen pictures of circles within circles so I thought, "Why not?"  I get to wear both this way LOL.  Besides, DH said he would buy it for me  So far, I don't have the ring yet, but hopefully it will be here this week!  I would like a nice diamond for the center.

Welcome MissDymonds666 !
There has been a lot of good points brought up here.
Let's start with the price of diamonds, going up exponentially as it goes past 1 carat.
Exponential actually is a very good word, because the price it does get get higher as you cross certain carat barriers, and then you have to pay for that much more diamond.
Let's say three quarter carat size diamonds are $3000 per carat.  If we multiply $3000 x 0.75 (three quarters of the carat), we get a net cost of $2250 of the three quarter carat diamond.
If we are looking at a diamond of the same color clarity and cut quality as the three quarter carat diamond, which was $3000 per carat.  The one carat diamond would likely be about $4000-$4500 per carat-and you've got to buy the whole one carat at that point to.
That means a comparable 1.00 to the .75ct would be $2250 versus approximately $4000.
Sounds pretty exponential to make.

Your take on the New York diamond District is correct too.  What we offer is exactly what you mentioned.
People don't have to find the upstairs office through a third-party.
They find us online, and we are their upstairs office.

There was also some talk of modifying rings and GIAgirl was correct.  It's much more difficult to try to change a ring, as compared to just making it from scratch the right way.
In some cases it is easy to set a new diamond into a ring that had a stone of similar size.  It's a case-by-case thing.


I also agree that it's important to look for good value when you buy.  As strange as this might sound.  I never try to buy our diamonds at the cheapest possible price.  There's a lot of reasons for this, for one I want to see the best diamonds.  Every time I look.  I'm not saying that I will pay 20% more than the next fellow but in many cases.  I don't mind paying 3 or 4% more than another dealer who is trying to get the cutter to sell for less.  I know that over time, the cutters want to show me their Best diamonds
The net result is that we get to see the best diamonds before the guys were trying to buy it for a few percent less.
When it comes to what we need to pay for setters, polishers, and the people who make our rings, at that point is absolutely no way to negotiate for a better price.
I would far prefer paying $50, as opposed to five dollars to set one of our fancy colored diamonds-if the setter is worth $50.
Thankfully, we've found setters that are worth that much. 
Welcome to the forum have a great time!!

Funny, there's never any simple answers in this thing.
I suppose I should mention that attempting to buy diamonds right below a size barrier, to try and save money, is generally not possible.
The reason?
Well, it's very simple for a cutter to save a few points.
For this reason, 1.00 carat diamonds are far more common than .99 carat diamonds. 

Once we get into more valuable diamonds, such as carat and a half and larger, stones that butt up against the next larger barrier are generally priced very close to those of the larger carat size.

For example, a 2.95 carat diamond is not worth all that much less than the 3.00 carat diamond of the same cut color clarity.
The list that dealers use to ascertain that the value of particular gradients is calibrated between 2.00 to 2.99 carat.
When a cutter cuts a 2.99 carat diamond, he's just not going to base his sale on the two carat list.