Based on the design of the conventionally-powered Agosta-class, the first batch of two Rubis-class boats was plagued by high noise emissions. This resulted in a significant re-design, originally applied stating with the fifth vessel, which eventually became known as the Amethyste-class. Actually, all the earlier Rubis-class submarines were refitted to this standard, becoming virtually indistinguishable from each other. That said, four of the earlier vessels have experienced significant incidents in their careers and the one, Saphir, was taken out of service in 2019, followed by Rubis in 2022. Moreover, the last two planned boats (Turquoise and Diamant) were eventually cancelled. The resulting fleet of four SSNs now known as the Amethyste-class (including the namesake, hull-number S605, commissioned to service in 1992, and Perle, S606, commissioned in 1993, but also earlier and rebuilt Casabianca and Emeraude) is based in Toulon and forms the Nuclear-Powered Attack Submarine Squadron (Escadrille de sous-marins nucléaires d’attaque). (Artwork by David Bocquelet)