The Diamond A Ranch also known as The Big Boquillas is the largest cattle ranch in Arizona. The ranch covers 750,000 acres and stretches 75 miles beginning at the town of Seligman and ending at the South Rim of the Grand Canyon. In 1982 Harvey Dietrich and then partner Richard Rudnick took over the Diamond A Ranch from Victorio Cattle Company. They operated under the name Cholla Livestock and in 1995 Rudnick sold out to Dietrich. For the next 22 years Harvey Dietrich operated Cholla Livestock and the Diamond A Ranch and in 2018 at the age of 83, Dietrich took on a new partner at Cholla Livestock with Rick Kieckhefer of the K4 Ranch, deeply rooting Cholla Livestock’s operation of the Diamond A ranch for years to come. The ranch has an extensive cattle operation running 6,000 head of mother cows and when the grass allows a seasonal herd of steers are grazed on the ranch. The Diamond A prides itself on producing high quality cattle to be marketed as natural beef to consumers across the country.  

There are 10 full time camp cowboys employed by the ranch to look after the 7 ranch camps and additional cowboys are taken on for the spring and fall wagons. Most pastures on the Diamond A are larger than your average ranch so the importance of strong working horses is a high priority. The size of the pastures of the ranch and their remote locations demand the use of horses that are both athletic and tough enough to be able to withstand the rigors of a typical day of work. These horses are used to brand calves, gather cattle, sorting cattle in the corrals as well as outside in a herd, check fence, gather horses, halter break weanling foals, doctor cattle and cover a whole lot of miles through all different kinds of country.  These horses are hearty and live almost their whole lives out in pastures making a living.

The Diamond A currently runs a remade of 75 working saddle horses, 30 broodmares, 3 stallions, and 35 young geldings and fillies. All the horses are run outside in the same tough country they work in. The blood lines of the ranch are mostly from cow and ranch horse stock and include Tanquery Gin, Doc O’Lena, Colonel Freckles, Peppy San Badger, Bueno Chex, Driftwood, Zan Parr Bar, PlayGun, Easy Jet, and Doc Tom Tucker. 

The horses and cowboys of the Diamond A are part of an old cowboy tradition that continues to live on throughout the southwest and with a strong dedication to people, cattle, and horses the Diamond A strives to continue as a leader in the industry.