I just received my copy of the 2012 Standard Catalogue of British Coins: Coins of England and the United Kingdom, 47th Edition (SCBC hereafter). The SCBC is an indispensable reference for the collector of British coins, and features reference numbers, photographs, descriptions, and estimated values for the coins.

The SCBC values are given according to each coin’s condition using the conventional states of preservation used for world coins (e.g., Fine, Very Fine, EF, UNC), rather than the Sheldon Scale that many collectors may be more accustomed to seeing. I thought it would be useful to provide a comparison of the conventional and Sheldon scales, along with a consistent approach to deriving a more refined estimated value than what is listed in the SCBC.

There is a good discussion of how Spink arrived at their values in the introduction that I won’t reproduce here, but the values differ from those you may find in other sources that change during the course of the year in response to changes in market conditions and bullion values.

The example table below is laid out in columns showing the SCBC reference number, a brief description, Sheldon Scale values, conventional grades, the conventional grade values from the SCBC, the calculation used to determine the amount to be added for each step above a given SCBC condition value, and the derived value once the step value is added to the value of the next lower grade. You will want to build a similar table for each coin you wish to evaluate. Setting it up in a spreadsheet will save you a lot of trouble.

In this example, to determine the derived value for an 1848 gold sovereign with a Sheldon Scale grade of AU 55 (conventional grade Good EF+):

- The values for an 1848 gold sovereign in each grade, found on page 438 of the SCBC, are already shown in the “SCBC Value” column.
- Calculate the step addition by subtracting the SCBC value for EF from the value for UNC, dividing by 5 (the number of steps between EF and UNC) and multiplying the remainder by 3 (the number of steps AU 55/Good EF+ is above EF); ((£1200-£700)/5)*3 = a step addition of £300.
- Add the step addition to the base SCBC value for EF to yield a derived value; £700+£300=£1000. This is the derived value for an 1848 gold sovereign in AU 55/Good EF+ condition.

You can make similar tables for any coin listed in the SCBC by entering the values shown in the “SCBC Value” column, performing the calculations in the “Step Calculation” column, and entering the results in the “Step Addition” and “Derived Value” columns. If you have the calculations set up in a spreadsheet, it’s as simple as replacing the numbers in the “SCBC Values” column.

There are a few limitations to this approach:

- The SCBC typically does not provide values for coins in FDC condition, so step calculations above UNC have to be based on further increases to the EF-to-UNC interval. In the above example, I assumed a coin in FDC condition to have double the value of UNC condition. In practice, this assumption is probably unrealistic – an extremely rare coin in top condition can be almost priceless! When examining very high grade coins, both this approach and the SCBC values themselves will need considerable adjustment based on experience and the coin being considered.
- In some cases the SCBC does not provide values for a given condition; for example, no values above VF are provided for any hammered coin. In these instances, you may have to base further increases on the F-to-VF interval. With regards to many of the hammered and ancient coins, there are so few examples in EF and higher that it would be very difficult to give a value; this could also apply to the very top grades of any other type.
- Finally, the SCBC provides no values at all for coins below F condition. I guess they figure the coin’s value is either its bullion value or completely subjective.

I have been using this approach for quite some time and while it isn’t perfect, it at least provides a rough guide (just like the SCBC) that is of use in determining the relative value of middle grade and common coins. As a check of its validity, it is worthwhile to see if you can find realized prices of similar coins from recent auctions. They do not have to be in the same condition. Compare the realized price against the determined value in your table, keeping in mind that realized prices often vary due to changing conditions as mentioned previously.

My thanks to Mr. Jon Blyth for his review of and comments on this article.