This in an expensive boutique brand they use the highest quality fabrics there is no fabric tag but it feels like cotton.

You can see the tag stitching on the back

New without tags Navybleu women’s blouse in size Small. Beautiful deep navy blue with a long self-tie neckline that can be worn tied in a bow or left loose. Features a button-front closure, long sleeves with button cuffs, subtle gathering at the shoulders, and gathered detailing across the back yoke.

Fabric content tag is not present. Fabric feels like a high-quality cotton or cotton-blend, but exact fiber content cannot be confirmed.

New without tags and unworn. Please note there are two small areas at the upper back where the original tag appears to have been attached/removed, as shown in photos.

Classic preppy, coastal and polished style that works well for office, business casual or everyday wear.