Sometimes these certifications will appear on the garment tags them self, unless the company only uses one material (like all organic cotton), the garments should be individually tagged with these identifiers. Look for them on the companies website or the garments hang tag (the paper tag that has the information about the garment.
Certified Organic. Only for natural fibers, particularly cotton. Denotes certified organic fibers.
Certified 100% Recycled Content.Measures percent of recycled content so companies can make accurate claims.
Global Organic Textile Standards. A global version of the USDA organic.
Certified X% Recycled Content.
Bluesign A "system is the solution for a sustainable textile production." Bluesign helps ensure textiles are produced in sustainable ways.
You might see these certifications either apply directly to fashion retailers (on their website, or as something they advertise) or directly to the factory, which the retailers then advertise. You might also see these on hang tags for items.
Social Accountability International. (SA8000) Standard Certifying good worker pay and labor rights.
Certified Fair Trade. Denotes certification of environmental and ethical standards for companies.
Textile Exchange. Helps companies find sustainable supply chains, focusing on making recycled textiles easier to find.
Fair Wear. Helps companies improve their worker safety and rights, focusing on manufacturing.