Three pieces of information tell you where a duvet sits in its category, and a listing that omits them has answered the question by omission. Those three are the fill weight for the specific size you are buying, a certification licence number you can look up, and the care instructions for the insert. Every brand knows all three. Choosing not to publish them is a decision rather than an oversight.
Weight per size is the first. Fill weight scales with the size of the duvet before it says anything about warmth, so a figure quoted without a size is unusable. A published table looks like this: an organic cotton insert running about 7.5 pounds in Twin, 10 in Queen and 12 in King, and an organic wool insert running about 6.5, 9 and 11.5. To compare warmth between two duvets you need GSM or tog instead, since both hold steady across sizes while total weight does not.
Second is the licence number. A certification claim is worth what you can verify about it. Global Organic Textile Standard certification names an independent certifying body and issues a number, in our case licence GOTS-10229 through Oregon Tilth, covering the finished duvet rather than only its shell. An eco friendly label with no number attached leaves nothing to check. Note that seals are material specific: OEKO-TEX Standard 100 tests a finished item for harmful substances, which suits a latex fill, while GOTS covers growing and processing as well as chemistry, which suits cotton. The useful question is whether the seal matches the fibre in the bag.
Third is care. The care instruction for an insert is a consequence of how it was built, so a listing that hides it is hiding the construction. A batted natural fill arrives as a connected sheet and comes apart in a washing machine, which is why the instruction is spot clean and sun only, with the duvet cover doing all the laundry. A loose synthetic fill washes without argument. Those are two different products and the care label is where the difference becomes visible.
There is a fourth thing worth reading, though its absence is less damning: how the fill is held in place. Loose down clusters and blown synthetic fibre migrate to one end unless something stops them, which is what baffle box walls and sewn through channels are for. A connected batted sheet holds its own position and gets anchored with hand tied corner loops instead, and those loops are what the ties inside a duvet cover attach to.
Read those four before reading anything on the front of the packaging.
Originally published on [Circadian](https://circadianrest.com/blogs/pillow-talk/6-things-look-down-alternative-duvet).
