This diamond was grown HPHT - intentionally blue.
I'm sometimes tempted to describe the color as "natural"... oddly enough for a lab grown diamond. The reason is that the color, emanating from the rough diamond, as opposed to treatment - is more like a natural blue diamond. The color is lighter - less distinct than most Lab blues.
The stone is beautifully cut.
There's no dark area in the center, but inherent in oval brilliant diamonds, there are smaller facets at the ends. These smaller facets create more sparkle - they draw a bit more of the blue color. The center has a lot of larger flashes.
The overall effect is bright and sparkly.
Great stone at a great price.