Engaging an antique coin dealer can be an enlightening experience, offering you a glimpse into historical eras and cultures, as well as an opportunity to build a collection of precious artifacts. However, it is not a venture to be taken lightly. There are multiple facets to consider when seeking the service of an antique coin dealer. As such, there are several things that, in retrospect, I wish I had known prior to engaging one.

• Understanding Coin Grading: The condition of a coin, known as its grade, significantly affects its value. The Sheldon scale, ranging from 1 (poor condition) to 70 (mint condition), is the standard used by antique coin dealers. It is an intricate system, with nuances that take time to comprehend.

• Numismatic vs. Bullion: Numismatic coins are those whose value is based on rarity, demand, condition, and mintage, rather than just their metal content. Bullion coins, on the other hand, are valued based on their precious metal content. Knowing the difference can affect your investment strategy.

• Market Volatility: The market for antique coins can be volatile, with prices fluctuating based on myriad factors including geopolitical events, economic shifts, and changes in collector trends. Even subtle shifts in metal prices can impact the value of antique coins.

• Historical Importance: Understanding the historical context of a coin can greatly enhance its value. Coins often reflect significant events, eras and patterns of civilizations. The deeper your knowledge, the better equipped you are to gauge a coin’s true worth.

• Reputation of Dealer: Not all antique coin dealers are created equal. Reputation is crucial in this business. Researching the dealer’s history, reading customer reviews, and checking their standing with professional organizations like the Professional Numismatists Guild can provide valuable insights.

• Counterfeit Coins: The proliferation of counterfeit coins in the market is an unfortunate reality. Familiarise yourself with common signs of counterfeit coins such as incorrect weight, poor craftsmanship, and incorrect details.

• Liquidation: Antique coins can be a sound investment, but it’s essential to consider their liquidity. Some coins might take longer to sell due to limited demand, while others can be sold easily due to their popularity or rarity.

• Auction Vs. Direct Sale: Coins can be purchased directly from dealers, or through auctions. Each method has pros and cons; auctions can sometimes yield rare finds, but also may result in overpaying due to competitive bidding.

• Certification: Certified coins are graded by professional organizations like the Numismatic Guaranty Corporation or the Professional Coin Grading Service. Certified coins offer a level of trust in the grading, but they also cost more.

• The Law of Supply and Demand: The value of a coin can often be dictated by simple supply and demand mechanics. Rare coins with a high demand will sell for more than common coins with little demand, regardless of age or condition.

• Emotional Attachment: Coin collecting is often driven by passion. However, allowing emotional attachment to influence buying or selling decisions can lead to financial loss. Try to maintain a balance between your emotional and financial investment.

• Knowledge is Power: The more you understand about numismatics, the better off you’ll be. This includes knowledge of history, economics, and even metallurgy. Equip yourself with knowledge, and you'll be in a better position to negotiate and make sound decisions.

In sum, engaging an antique coin dealer can be a rewarding endeavor, steeped in history and offering financial benefits. However, it requires a significant investment of time, research, and due diligence. It is a journey worth embarking upon, armed with knowledge and a keen eye for detail.