User Review: Comparison of Different Apps

Background

We have received a very detailed review from David on gold coin verification. He compared our app with two other similar apps on the market, using four different types of gold coins (a total of 160 coins).

David thanked us via email and included the complete version of his review as an attachment.

The Review

We have included the original text that David sent to us directly below without making any changes (except for formatting) to avoid any bias:

Precious Coin Tester, Ping Coin, and Coin Tester coin ping apps were tested. Krugerrand, 100 Corona, $20 USA Double Eagle, and Mexican 50 Peso coins were tested simply to determine if the coins were made of gold. The three programs were downloaded onto an HP Chromebox G3 personal computer. All three programs worked immediately with no problem. A Logitech C920 Webcam was used for sound detection.

The Precious Coin Tester app provides free use for all tested coins except for the Mexican 50 Peso. The composition of the gold alloy for the Mexican 50 Peso is the same as a USA Double Eagle, and the Double Eagle choice was used to test the Mexican 50 Peso.

The coin apps have 3 positive rankings: Adequate, Good, and Great. A mixture of 160 coins made from the 4 coins listed above were tested using a $12 bar ping test tool from eBay, as shown in Figure 1.

The 100 Corona tested 100% Great, Krugerrand 100% Great, USA Double Eagle 100% Great, and all Mexican 50 Peso tested 100% adequate. Most coins tested great with one test. The Precious Coin Tester app worked very well with the mic 18 inches from the coin. All coins were tested with the mic about 2 inches from the coin. The app worked best striking the coin lightly and producing a light ring. A hard strike producing a beautiful, loud, and long ring would sometimes cause the app to return a “Too Noisy” response. The system worked best when the sound was just audible. A light ring was best obtained when holding the coin at a 45-degree angle and striking the coin lightly on the rim as shown in Figure 2.

Ping Coin only provided testing for a 100 Corona. All coins tested good.

Coin Tester only provided testing for a Krugerrand. Several different Krugerrands of various dates were tested, but no results, either positive or negative, were obtained.

Short Version on Google Play

Google Play does not allow comparisons in the review section. David's first review was rejected for including such content, which prompted him to send us the original review. He later removed the comparison section and posted an updated version of the review, now available on Google Play.

Important Note

David attempted to use the USA Double Eagle setup to test a Mexican 50 Peso coin. This approach is incorrect and yields meaningless results.

The Mexican 50 Peso and the USA Double Eagle differ in size and weight, resulting in unique sound signatures, even though both are 90% gold. Using the USA Double Eagle setup to test a Mexican 50 Peso coin disregards these differences and leads to inaccurate and misleading outcomes.

For example, David’s test result—stating that all Mexican 50 Peso tested 100% adequate (i.e., a 1-star result)—is invalid. We have shared this concern with him.

So, always ensure you select the correct coin for testing to obtain reliable and meaningful results.