We buy and sell coins among many other items. Our USPAP appraisals are backed with thirty years of numismatic experience. We work with coin collectors, dealers, auction houses, historical societies, and educational institutions.
Meet the Team
We specialize in coins, currency, collectibles, jewelry, antiques, fine art and more. We work with common and rare metals, and all types of coins including US Coins, foreign currency, ancient coins, mint and proof sets.
Marc Alan Rosner
A passion for coins, currency, safes and locks, and helping people
I hold a B.A. in Historical Archaeology from Wesleyan University, and an M.A. in Science Education from Columbia University. I have over 30 years of experience collecting and dealing in rare items and enjoy meeting people and hearing stories about the things that they have. I publish and write articles and books on science and numismatic education.
In June 2024 I retired from teaching high school and middle school science and am fortunate to now be a full-time numismatist. I started Hudson Valley Numismatics over 20 years ago when someone sought me out about selling their collection and I realized I could turn my hobby and passion into a business.
Diane Gross
New to numismatics but not small business
With a B.A. in Health and Society from the University of Rochester and a Master in Public Health from Columbia University, what am I doing in the coin and estate business? After a 30-year career, I was incentivized to make some changes. Marc and I met in 2018 and married in 2024. We both were at pivotal points in our day jobs and have decided to expand our partnership to business and work full-time helping people with their estates. We are now a family business.
With previous small business experience and years of working in the non-profit space doing a bit of everything, I am working on social media, website content, operations, auctions, business development, marketing, and learning.
We Proudly Support Local Youth and Education
We are proud to have had the honor of donating goods and services to the following institutions and charities: The Hastings Historical Society, the Dobbs Ferry Historical Society, the Tarrytown Historical Society, the Hastings Education Foundation, the Ardsley Education Foundation, and the Village of Hastings-on-Hudson Recreation Department.
Court-Approved by the State of New York
Marc Rosner is on the New York State Part 36 fiduciary list — the official roster of professionals approved by the NY Unified Court System to serve in court-appointed roles. For coin and currency collections moving through estates, trusts, guardianships, or contested probate, a Part 36 appraisal carries the weight a judge needs.
Show the verification details
Inclusion on the Part 36 list is not automatic. It requires a vetted application, ongoing eligibility review, and active certification by the state. Marc holds Fiduciary ID #107338, is registered in Westchester County, and is eligible through January 2027.
Verify on the NY Courts website →Third-Party Certification Services Member
We have memberships at, and submission privileges to, the major third-party authentication services for all tiers of service. We can submit coins and paper money for evaluation and encapsulation to Professional Coin Grading Service (PCGS), American Numismatic Association Certification (ANACS), Numismatic Guaranty Company (NGC), Certified Acceptance Corporation Grading (CACG), and Paper Money Guaranty (PMG). We also advise on the submission, appraisal, purchase, and sale of certified coins.
A.N.A. Life Member
After receiving his 25-year membership pin, Marc became an American Numismatic Association Life Member. He has full admission to all A.N.A. Conventions, has taught at their Summer Seminar, has full access to the Dwight N. Manley Numismatic Library—the largest in the world—and is bound by the A.N.A. code of ethics.