[QUOTE=LaurieB;6444451]
Since there’s no central registry, it’s almost impossible to know what colors and patterns have already been used, or are currently in use, so most people just design something they like and go with it.[/QUOTE]
Thanks Laurie. Sounds like another segment the “Horse Racing Commissioner” (or the Government) can have control of 
This 2010 article suggests the Jockey Club is the keeper (and registrar) of records for New York State with silks and stable names.
Silks designs generally are not regulated around the country. But if owners expect to race a horse in New York, whether on a cold winter’s day at Aqueduct or in June in the Belmont Stakes, they must register the silks with the Jockey Club. And that will lead them to an office where Lee Weil and Mary Keiser sit.
“Blue and white stripes,” Keiser said over the phone to someone in the Color Room, describing a stable’s design. “White sleeves. Blue hoop. O.K.?”
The Jockey Club has registered silks for more than 100 years. On a recent day, Keiser held the application for No. 31,632. But there is little fear of running out of design combinations.
[i]By registering stable names and silks with The Jockey Club, an owner is guaranteed exclusive use of the stable name and silks design when racing Thoroughbreds in New York State.
However, owners who race horses in other states are welcome to, and often do, register their stable name and silks with The Jockey Club as well. [/i]
http://home.jockeyclub.com/silks.asp
Silks Registration Fees:
First-time silks registration - $100
One-year silks registration renewal - $25
Five-year silks registration renewal - $100
The rules of what you can/cannot do (in NY) appears to be more “tight”
- Front and back of silks must be identical, except for seam design.
- Colors must be registered in the name of one person only; NOT a stable name or Mr. & Mrs. (example: Mary E. Jones).
- Designs are limited to those on the reverse side of this form.
- Navy blue is NOT an available color.
- A maximum of two colors is allowed on the jacket and two on the sleeves for a maximum of four colors.
- These colors will be renewable on December 31st of the year they are registered.
- You may have an acceptable emblem or up to three initials on the ball, yoke, circle or braces design. You may have one initial on
the opposite shoulder of the sash design, the box frame, or the diamond.