Led filaments with light-reflective particles for providing sparkle

A light-emitting diode, LED, filament comprising:

• an elongated substrate;
• a plurality of light-emitting diodes, LEDs, mechanically coupled to the substrate;
• an at least in part light-transmissive encapsulation encapsulating the plurality of LEDs and at least partially encapsulating the substrate;
• and
• a plurality of at least partially light-reflective particles arranged on an outer surface of the encapsulation,
• wherein a particle of said at least partially light-reflective particles comprises:
• a first face lying against the encapsulation, and
• a second face opposite to the first face, said second face facing away from the encapsulation,
• wherein a particle of the at least partially light-reflective particles has at least one flat surface and is characterised by a longest dimension length (L1), a shortest dimension length (L2), and a further dimension length (L3) and,
• wherein a first aspect ratio between the longest dimension length and the shortest dimension length, AR1=L1/L2, is in the range 10-300, wherein a second aspect ratio between the further dimension length and the shortest dimension length, AR2=L3/L2, is in the range 10-300 and wherein a third aspect ratio between the longest dimension length and the further dimension length, AR3=L1/L3, is in the range 0.3-3.