This video compares, from left to right, a Charles and Colvard forever one Oval Brilliant moissanite, Natural Diamond Oval Brilliant, and Harro Gem Oval Diamond Cut Moissanite.

The video also shows each stone in direct sunlight, shaded, and LED lighting settings.

The main difference between Charles and Colvard and Harro Gem are the goals for the moissanite for each company. Charles and Colvard want to maximize the brilliance of moissanite. Harro Gem wants to create moissanite that looks as close to a diamond as possible. 

Visual Comparison

1. Forever One Brilliant Oval - The forever one is very clear and has the strongest fire between all of the stones. The forever one has an appearance similar to a round diamond, meaning that you are able to see each individual facet. The diamond and Harro Gem both have a more "crushed ice," appearance.
2. Oval Brilliant Diamond - The diamond will have the most depth, and looks like an endless vortex of glitter. Diamonds do not have as much fire as moissanite, but a good quality diamond will have clearer material. Even the best moissanite can have a slightly hazy appearance when compared to a diamond. 
3. Harro Gem Diamond Cut Oval - The Harro gem is faceted to be as close to the look of a diamond as possible. It has a much more subtle fire and brilliance when compared to the Charles and Colvard moissanite. It also has a more hazy look when compared to the others. 

Durability & Quality

1. Forever One Brilliant Oval - Hardness of 9.25, Colorless, VS+ in clarity
2. Diamond - Hardness of 10, Large range of colors and clarities
3. Harro Gem Diamond Cut Oval - Hardness of 9.25, Colorless, VS+ in clarity

On the Moh's Scale of Hardness Moissanite will be harder than sapphires and rubies which are corundum at a hardness level of 9. However, a diamond is still exponentially harder and more durable than any other material. 

Pricing 

1. Forever One Brilliant Oval - In the most popular sizes 1ct-3ct the prices range from $325-$1095. You can check out other prices for more sizes here.
2. Diamond - In the most popular sizes 1ct-3ct the prices range from $3000-$32,000. Diamonds are available in a much wider variety of qualities, so the price variation is much more extreme. The parameters we used for the search were 1-3ct, D-F color, SI1 Clarity, GIA Graded, No Fluorescence. If you need help with shopping for a diamond and finding the parameters you are looking for feel free to contact us and we will help you get started.
3. Harro Gem Diamond Cut Oval - In the most popular sizes 1ct-3ct the prices range from $500-$1450. You can check out other prices for more sizes here.

Conclusion

For the value and durability, you get from moissanite for your money, it's tough to beat. Moissanite definitely has a unique look when compared to a diamond, and the price is typically the main deciding factor for most people. If you have the budget for a diamond and prefer the look and appearance of a diamond there are great options in both lab-grown and natural varieties.