Butterfly Knife | Doppler Sapphire (BFK Sap) was added to the game on March 15, 2017, alongside the "Take a trip to the Canals" update. The skin is available in cases "Spectrum" and "Spectrum 2".
The blade of the knife is painted with metallic paints and adorned with a pattern of translucent wavy lines resembling smoke. The color scheme of the skin includes various shades of blue creating gradient transitions. The design of the skin resembles the texture of the sapphire. The handle is unpainted and complemented with dark blue inserts.
Float Value of the skin ranges from 0.00 to 0.08, which makes Butterfly Knife | Doppler Sapphire available only in Factory New and Minimal Wear condition. At levels of wear close to the maximum, the knife has noticeable scratches and abrasions located along the cutting edge.
The pattern index affects the texture overlay. Special or rare variations of the pattern are absent.
The quality of Butterfly Knife | Doppler Sapphire is Covert. The skin has a StatTrak option and is not the rarest but the most expensive phase in the “Butterfly Knife | Doppler” series.
“Doppler Black Pearl” is one of the rarest skins for M9 Bayonet and is highly valued by skin collectors. Due to a high price, M9 Bayonet | Gamma Doppler Black Pearl is rarely seen in the game.