# Fallacy vs Gem Identifier & Rock ID

The clearest difference is ads: Fallacy at none against Gem Identifier & Rock ID's shown. Fallacy also leads on update cadence (fortnightly vs monthly) and device support (3 vs 1). On price, rating, ratings volume and in-app purchases there is nothing between them.

Both are free to download. Fallacy sells 4 in-app purchases, starting at $6.99 per 7 days and Gem Identifier & Rock ID sells 5 in-app purchases, starting at $6.99 per 7 days. Whichever you choose, the download price is not the number that matters.

On the App Store both sit at effectively the same score — 4.5 for Fallacy against 4.4 for Gem Identifier & Rock ID. Both are backed by a comparable volume of ratings — 57 and 21 respectively.

Fallacy ships an update fortnightly, Gem Identifier & Rock ID monthly. The most recent releases landed on September 23, 2026 and September 18, 2026 respectively.

## The numbers

| Metric | Fallacy | Gem Identifier & Rock ID |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.5 (57 ratings)](https://appshunter.io/ios/app/fallacy-brain-training-logic/id6743923575/reviews)** | [4.4 (21 ratings)](https://appshunter.io/ios/app/gem-identifier-and-rock-id/id6748907151/reviews) |
| Number of ratings | **57** | 21 |
| Positive reviews | 76.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | **No** | Yes |
| Update frequency | **Fortnightly** | Monthly |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 95 MB | 36 MB |
| Requires iOS | **15.1** | 16.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [VERTEX STUDIOS LTD](https://appshunter.io/developer/1805080787) | [Innotent LTD](https://appshunter.io/developer/1695717745) |

## What reviewers say

### Fallacy

[App page](https://appshunter.io/ios/app/fallacy-brain-training-logic/id6743923575)

This app teaches logical reasoning and critical thinking skills by turning the identification of logical fallacies and cognitive biases into a game. It offers structured brain training with daily exercises and timed challenges, using real-world scenarios and media to build applied intelligence.

**Highlights:** Identify 30+ logical fallacies, Recognize 20+ cognitive biases, Daily brain exercises, Timed reasoning challenges, Debate Mode with real-world arguments, Progressive difficulty levels

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly Premium Access | $6.99 | per 7 days |
| Monthly Premium Access | $12.99 | per month |
| Yearly Premium Access | $39.99 | per year |
| Lifetime Access - Premium | $79.99 | one-time |


### Gem Identifier & Rock ID

[App page](https://appshunter.io/ios/app/gem-identifier-and-rock-id/id6748907151)

Identify rocks, gems, and crystals instantly by taking a photo. Access a comprehensive database with detailed information and authenticate precious stones. Includes a built-in metal detector for further analysis.

**Highlights:** Instant stone identification via photo, Comprehensive stone database, Gem authentication tool, Built-in metal detector, AI recognition technology

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly | $6.99 | per 7 days |
| Yearly | $19.99 | per year |
| Yearly, 3 Days Free Trial | $29.99 | per year |
| Yearly | $29.99 | per year |
| Lifetime | $14.99 | one-time |


## Frequently asked questions

### Is Fallacy free?

Fallacy is free to download, with in-app purchases available.

### Is Gem Identifier & Rock ID free?

Gem Identifier & Rock ID is free to download, with in-app purchases available.

### Which has better reviews, Fallacy or Gem Identifier & Rock ID?

Fallacy is rated higher. Fallacy averages 4.5 out of 5 from 57 ratings, while Gem Identifier & Rock ID averages 4.4 from 21 ratings.

### Do Fallacy or Gem Identifier & Rock ID have ads?

Gem Identifier & Rock ID shows ads; Fallacy does not.

### Which is updated more often, Fallacy or Gem Identifier & Rock ID?

Fallacy ships an update fortnightly, and Gem Identifier & Rock ID monthly. Most recently, Fallacy was updated on September 23, 2026 and Gem Identifier & Rock ID on September 18, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*