Diamond Mountain Stables (DMS), located in the foothills of the Napa Valley, was established in 1983 by Calistoga High School sweethearts Macella O'Neill and Charles White.

Their goal was to develop a business, training and competing with jumping horses.

They began with one black race horse and a couple of local students.

Over the years Macella's life long love of horses and Charlie's keen sense of business
have garnered an international reputation in the world of show jumpers.
In addition, the students and horses that they have coached and trained are often found in the winners circle at the most prestigious competitions, while O'Neill and White have successfully competed in World Cup Qualifiers.

Despite these amazing accomplishments, Macella and Charlie continue to be known for their deep love of horses and respect for these magnanimous creatures. They have an uncanny ability to develop both horse and rider.