The blue diamond is, alongside the red, one of the rarest stones in existence — both in nature and in the laboratory. Its mysterious beauty has transcended centuries and legends, culminating in the most famous of them all: the Hope Diamond.
The Science of Blue Colour
Unlike the yellow diamond whose colour comes from nitrogen, the blue diamond owes its tint to the presence of boron atoms in its crystal lattice. Boron absorbs red and yellow wavelengths of light, allowing only blue tones to pass through. The higher the boron concentration, the deeper the blue.
The colour range is exceptionally wide: from pale, luminous blue-grey to deep royal blue, with turquoise or blue-green nuances that make each stone a unique piece.
The Hope Diamond
The most celebrated blue diamond in history is undoubtedly the Hope Diamond — a 45.52-carat stone of deep blue, today housed at the Smithsonian Institution in Washington. According to legend, it belonged to the French Crown before being stolen during the Revolution. Having changed hands many times, it acquired the dark reputation of being cursed. Its appearance in the film Titanic only strengthened its legend.
Laboratory Production
Reproducing a blue diamond in a laboratory requires extreme mastery of boron concentrations in the CVD process. The slightest variation can alter the shade or create irregularities. This difficulty is what makes a high-quality blue diamond a stone of exception, even among lab-grown diamonds.
Its rarity makes it all the more precious — a blue stone on a woman's finger is a declaration of absolute uniqueness.