The four C's of diamonds are easy to identify: Carat, Cut, Color, Clarity. The four C's of a brand? Maybe not so much. Here, we ask Pietra's jewelry designers to tell us what makes up their four C's: who is their dream celebrity? What is a common trait of all their amazing clients? What is the most prized piece from their collection, and what is unique about their craft.


Vanessa Paradis and her daughter Lily Rose Depp. I can totally picture Vanessa with my Ani necklace and Lily Rose with a Camelia ring.


It's very difficult to answer this question since Sophie d'Agon's customers are so varied. [The brand] seduces 20-year-old, less conventional women, as well as much more mature women, who are more classic. One thing they have in common is that they are looking for a different piece of jewellery that they will wear for a long time.


The Ava earrings have an art deco look that I love and they are fitted with marquise cut stones. I love marquise cut stones even more since I discovered the origin of their name: King Louis VI had stones carved in the shape of his mistress' lips the famous marquise de pompadour.


The finesse of the frames to give the maximum relief to the precious stones and the original mix of colours is what truly sets this line apart.