Robert Ridgway was a famous ornithologist who wrote an eight-volume work on The Birds of North and Middle America. (Three more volumes were completed by a colleague after his death.) He saw a need for standardized color naming in ornithology and other sciences that had to classify large quantities of natural specimens, and published a system for identifying and naming 1115 colors in 1912.

Ridgway's Color Standards and Color Nomenclature was not the first attempt to standardize colors. Taxonomies of 100 to 400 color names had been published through the 19th century and more rigorous systems based on spectrum analysis or color-wheel placement had used symbols or numbers to represent exact combinations of color features (hue, tone, light, shade, etc.). Ridgway's, however, was the first to provide such a finely divided color categorization that also used words from natural language, which, he argued, despite their imprecision, were more useful to naturalists.

The book was printed with 1115 painstakingly produced color plates, including more than 100 shades of gray. The names for those grays include mellifluous terms like plumbeous (the color of lead), plumbago (a flower with lead-colored petals), glaucous (from the Latin/Greek for bluish-gray), vinaceous (wine-colored), cinerous (cinder-colored), and heliotrope (a flower with purplish petals). Varley is named for landscape painter John Varley and Payne after painter William Payne. After you read this list, you can proudly tell all your friends you were intellectually stimulated by reading 50 shades of gray.

1. Cadet Gray
2. Carbon Gray
3. Castor Gray
4. Cinereous
5. Clear Blue-Green Gray
6. Court Gray
7. Dawn Gray
8. Drab-Gray
9. French Gray
10. Glaucous-Gray
11. Dark Glaucous-Gray
12. Deep Glaucous-Gray
13. Gull Gray
14. Light Gull Gray
15. Hathi Gray
16. Heliotrope-Gray
17. Dark Heliotrope Slate
18. Iron Gray
19. Lavender-Gray
20. Lilac-Gray
21. Mineral Gray
22. Mouse Gray
23. Blackish Mouse Gray
24. Neutral Gray
25. Dusky Neutral Gray
26. Olive-Gray
27. Payne's Gray
28. Light Payne's Gray
29. Pale Payne's Gray
30. Pearl Gray
31. Plumbeous
32. Blackish Plumbeous
33. Plumbeous-Black
34. Dark Plumbeous
35. Plumbago Gray
36. Dark Plumbago Gray
37. Puritan Gray
38. Purplish Gray
39. Pallid Purplish Gray
40. Sky Gray
41. Slate Color
42. Slate-Gray
43. Slate-Black
44. Blackish Slate
45. Smoke Gray
46. Storm Gray
47. Varley's Gray
48. Vinaceous-Gray
49. Deep Vinaceous-Gray
50. Violet-Gray