A pure carbon diamond with no impurities will grade as a colorless diamond. However, the majority of both mined and lab-created diamonds contain impurities, most of which are nitrogen. The nitrogen atoms within the diamond lattice create the yellow tint. In cases of fancy colored diamonds, a pure yellow color is created. Nearly all diamonds, both mined and lab-created, start out as yellow diamonds.
Over the span of millions of years and exposure to pressure and heat, mined diamonds split the nitrogen atoms within their lattice rendering the nitrogen atoms ability to produce yellow light. The splitting of the nitrogen atoms is what gives the diamond its ability to shine white.
In the case of lab-created diamonds, we don't have millions of years to convert a yellow diamond to white, however, the ability to grow the diamond with little or no nitrogen produces the same result.
Growing a white diamond requires an incredibly controlled environment. The heat and pressure must remain consistent through the entire growing process. Any fluctuation or change within the growth cell can cause the diamond to stop growing or can create heavy inclusions.
Extracting the nitrogen and boron from the growth cell to remove the color from the diamond lattice also causes the diamond to grow slower. White diamonds typically take up to two weeks or longer to grow a 1.0 carat stone.
It is the extended growth time, the need to extract certain elements from the growth cell and the demand to keep the heat and pressure consistent that makes growing a white diamond difficult, thus contributing to their limited availability.
Unlike earth mined diamonds, lab-created diamonds are very limited in supply. The process used to create a white diamonds is also the most time consuming and temperamental. Given that white earth mined diamonds are in abundance and white lab-createds are in limited supply, the cost ends up being very comparable. A typical 1.0 carat lab-created diamond will range from $5,600 to $10,000. White lab-created diamonds are priced identically to mined diamonds using the cut, carat size, color and clarity to determine their individual worth.
White diamonds yield a square-ish rough. This allows the most popular shapes to be produced: round, princess, asscher, cushion and emerald. These shapes compliment the diamond rough and in return give the highest yields. Elongated shapes like oval, marquise and pear typically aren't produced because of their need for a more elongated rough.
All lab-created white diamonds offered by most reputable jewellers are hand cut. Every diamond comes with individual certificates and shows their cut grade on the grading report. Every diamond is cut to maximize brilliance and color.
The clarity of a lab-created white diamond is evaluated the same as an earth-mined diamond, typically ranging from IF to SI2. All grading is done by certification laboratories and their certificates are included with every lab-created diamond offered by most reputable jewellers.
Diamond Clarity Scale Table
Flawless: No inclusions under 10x. A stone that is completely flawless. This is an extremely rare find.
Internally Flawless: No internal imperfections. A stone that has no internal flaws at all but does have surface flaws. Also, an extremely rare find.
Very Very Slightly Included: A stone with very minute internal inclusions that are extremely difficult to see under a 10X magnification.
Very Slightly Included: A stone with very minor internal inclusions that range from difficult to somehwat easy see under a 10X magnification.
Slightly Included: A stone that has imperfections visible under X10 magnification and may be visible with the unaided eye.
Included: A stone that has significant inclusions most often visible with the naked eye. Inclusions of this level drastically bring down the diamonds value.