The Numismatic Bibliomania Society



The E-Sylum: Volume 26, Number 47, November 19, 2023, Article 10


Justin Hinh has created an app using OpenAI's ChatGPT4 platform to provide coin identification and grading estimates. Here's his description. -Editor

Do you remember a few weeks ago when I brought up how OpenAI's artificial intelligence models were making major strides in generating realistic images of coins? Well, OpenAI just made another massive update with the release of GPTs. GPTs are a way to create highly customized ChatGPT apps.

I got access to it and in less than 10 hours I was able to create the initial alpha build of Numi, a fine-tuned version of ChatGPT4 specifically made to provide objective grading estimates and coin identification.

  Numi demo 1 Numi demo 2 Numi demo 3

You can upload up to 10 photos of a coin and the AI will run a combined analysis. You will get back info such as:

  • Short Description
  • Coin Type
  • Year
  • Mint Mark
  • Estimated Grade

What's cool is that you can continue the conversation with the AI to learn more about your coin.

  • Want to know who designed the coin?
  • Want to know why a certain symbol was used?
  • Just follow up and ask!

In order to access it, you will need to have a ChatGPT Plus subscription [paid]. But here is a video demo of the app in action in case you don't have a subscription.

AI is making massive gains and numismatists can now create any app they want. It's amazing how in less than I day I created an app to help automate grading. I'm excited to see what others have in store.

I don't make any money from this free app as I consider it a project to help out the community. I would welcome any feedback from readers. I'm looking for ways to improve the AI model and user experience. Readers can contact me via my email .

To watch the video demo, see:

That was last week. Here are Justin's updates. -Editor

I have significantly revamped Numi to be more accurate and concise. I have also integrated Numi to have access to Numista's database. Users can now just not only use Numi to identify and grade their coins, but they can also follow up and ask Numi for additional facts about their coins. Facts such as:

  • Mintage figures
  • Coin values
  • Coin details such as composition, diameter, weight, etc

One of the main parts of building Numi was giving it highly custom instructions and grading criteria. I've been actively testing Numi with my local coin shop and at coin club meetings. It has been honestly thrilling (and a little scary) when I pull out Numi and test it live out in the field. Some collectors were blown away. Others simply scoffed and brought up memories of Compugrade back in the 1990s.

Numi's grading is still not perfect, and there are still inconsistencies. But they are decreasing by the day with more testing and fine-tuning. Readers should consider that Numi is still in the alpha stage. It's very much a proof of concept right now to validate if AI models have gotten so good that AI grading is now truly viable.
I also got a web domain for Numi. Readers can use for easier access to the AI chatbot. Much easier than remembering

Ancient Coins
I updated Numi to handle identifying and grading ancient coins. Here are some results.

Denarius - Julius Caesar (CAESAR; Elephant)
AI Grade: Choice Very Fine (Ch VF)
Full AI Response

Denarius - Sextus Pompeius
AI Grade: Choice Very Fine (Ch VF)
Full AI Response

  Numi demo 6 elephant denarius Numi demo 7 elephant denarius Numi demo 8 elephant denarius

If I could relay one message to readers, it would be this. The full force of Artificial Intelligence is coming to numismatics very soon. It won't impact just grading, but everything. If ChatGPT4 is this powerful, just wait until we see the release of ChatGPT5 next year.

An online collector asked me why I built Numi. Below is a copy of what I sent to them:

"Over the years, I have observed how high the barrier to entry can be to coin collecting. It can feel intimidating for new collectors to build up the courage to go to a local coin shop or coin show. And once they are there, they are bombarded with words like grade, obverse, slabbed, mintage, and hundreds of other insider terms. No wonder so many new collectors only show up once and never return. With the rise of the younger generation of collectors, I felt it was important to make numismatics as accessible as possible.

"I have been closely following the developments of OpenAI and ChatGPT. In November 2023, OpenAI released GPTs and I got access. I knew this was the chance I was waiting for. Within just 10 hours of getting access, I developed the initial build of Numi, a fine-tuned AI chatbot designed to simplify coin grading and identification for collectors of all levels.

"I built Numi for the everyday collector. An example I imagine is Numi being used by a collector who lives far away from a coin shop. Before Numi, they would take a long drive to the coin shop, only to be disappointed to learn their grading estimate was off and that it wouldn't make sense to send their coin in to a third-party grader. With Numi, they could now see if it's worth it to make that drive."

Additional Materials
Here is a video of Numi in action

PF 69 2005 S Lincoln Cent

Photo of slab

  Numi demo 5 PR 69 slab Numi demo 4 PR 69

As seen in the video, Justin provided the app with photos of the two sides of the coin, not the complete slab and label. Based on its evaluation of the images, it matched the slab grade - Proof 69. -Editor

To Keep In Mind
In order to access Numi or any of the thousands of custom GPTs being made right now, users will need to have a ChatGPT Plus subscription to OpenAI [$20 a month].

If I can validate that Numi is viable, I will work on a more open and free version of Numi so everyone can have access. A heads up though, demand for GPTs got so high that OpenAI has temporary paused ChatGPT Plus signups. Hopefully they will allow signups again soon.

Request to the community
There are two requests I have for the community/readers. My first request is for high-quality photos of lower graded slabbed coins. I do not have any graded slabs between Poor (PO) and About Uncirculated (AU). I would need at least 8 high-quality photos [4 on each side]. I will provide the reader with a copy of the results and Numi's response.

My second request is for readers who consider themselves advanced/expert coin graders. Here is a link to a google word doc outlining the exact grading standards that Numi uses to grade coins. These grading standards were made using a combination of the top third-party grader's standards, as well as feedback I have gotten from experienced graders in the hobby. I am turning to the wisdom of the crowds to get their thoughts on the wording of these standards. If you would like to leave your thoughts to help make Numi more accurate, please consider leaving a comment in this google doc. Your feedback will be invaluable in making Numi more accurate for the hobby.

See the next article in this issue for some background on how the Numi app was created. -Editor

for more about Justin Hinh, see:

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Wayne Homren, Editor

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