What to look for: the composition on the label
At the risk of repeating myself and teaching you nothing new, always check the composition on the label when buying a coat. The mistake most of us make is to choose a coat based on its style and then its price. Or the other way around, but most of the time it is the price that will guide our purchase. While we should always look at the composition on the label first... and yes! The label, always ! Remember that we expect a coat to keep us warm (yes, style counts too) and that without checking the composition, it is difficult to judge. A coat with a good composition, that is to say a coat made of a good percentage of wool - at least 70% of wool is the minimum in my opinion - is often more expensive than the average (count at least 250 euros for a coat of good composition with a nice cut). But this is not always true. I know a lot of big brands that sell coats at a high price, sometimes close to 500 euros (!!!) while their composition leaves something to be desired. On the other hand, you can find very good coats with a good percentage of wool at very good prices, such as my camel coat Gisele from PROMOD, which I bought last year and that you seem to like a lot. For this coat, be careful because the percentage of wool varies according to the color... It is warmer in camel (75% wool) than in gray or navy (62%). It is enough to become a little goat, don't you think?
My advice: if a coat combines style and price but its composition is rotten: GET OUT, or you'll regret it (and freeze). Don't give in to the sirens of fashion and don't let yourself be tempted by the price, if you look hard enough you'll inevitably find the rare pearl that meets the three criteria for buying a winter coat: style, composition, fair price.
What is a warm coat?
a coat not too close to the body nor on the contrary, too big, otherwise you will be cold. The ideal is to have a little room to wear it with a thick sweater underneath or a "feather" down jacket. If I try a coat in which I feel tight in the shoulders or under the arms, I do not buy it. To be warm, you have to be able to move around comfortably.
A coat made of at least 70% wool (80% is even better but the price often doubles). The remaining 30% is usually synthetic material that makes up the lining. 70% wool is really the minimum. Wool is the most suitable fiber for winter coats because it is natural, insulating and breathable. It will protect you from the cold without making you sweat thanks to its thermoregulatory power.
a coat with cashmere, it's even better but you have to have the means (and you can't find many on the market).
avoid 100% polyester linings. Polyester makes you sweat, so imagine what it would be like in winter if your lining was 100% polyester. Besides, polyester pollutes, so avoid it as much as possible.
Note: some synthetic + wool blends can be warm but it depends on the thickness, the cut and other points to take into account. To see case by case according to your fittings but in doubt, always trust the percentage of wool in the composition.
Traps to avoid
And just to add a little more difficulty to find THE coat, there are some traps in which we can easily fall. This is the case of boiled wool coats for example! The boiled wool is a wool that we boil to relax the fiber and to be able to weave it then in a very tight way, we obtain a wool a little felted. It is normally supposed to keep warm, this technique was already used in the Middle Ages to make coats. But it really depends on the thickness of the coat, if there is a good lining or not... Personally I have never found a warm coat in woolen bouille in store. Uniqlo sells some boiled wool coats that seemed very light when I saw and touched them in store! To be seen on a case by case basis but 100% boiled wool does not mean "warm coat" at all!
The other trap you can quickly fall into is the wool sheet coat. The wool sheet is a great textile but it is its weight that determines if it is warm enough or not to make a coat or not. And as you can imagine, most of the woolen coats that you can find in the big stores are more like a sheet than a coat (ahah). Joking aside, it's really a material to avoid unless it's a really thick and warm wool sheet, in which case the price might be high too.