By smell: inferior silk duvets give off a slight smell of chemicals and silkworm pupae, which will become stronger during use in more humid and warmer environments. This smell is detrimental to health, especially to those who have an allergic constitution.
By colour: 100% natural silk floss has a soft and lustrous pearly colour; in contrast, as a result of bleaching, inferior floss looks artificially white and shiny.
By feel: pure silk floss feels more delicate yet less smooth than lower-grade floss, which has been treated by machines.
By the length of the silk filaments: The most exquisite duvets are made of long and unbroken Mulberry silk sheets, which are stretched and hand-layered one by one in a criss-cross pattern. The silk is very smooth and even throughout the duvet. In contrast, silk in machine-made duvets is usually broken. Shake the duvet quickly and, if it is made by machine, tiny dust-like fibres can be seen falling down from the duvet. If breathed in these fibres may be harmful, especially to babies and children.
By the durability of the silk filling: silk in handmade duvets is very flexible and strong. In contrast, silk in machine-made duvets is loose and fragile.