Natural diamonds display differences in their properties from man-made diamonds due to the different growth conditions in which they form.
The temperatures for natural diamond crystal growth and diamonds made in the laboratory are similar, but diamonds grow as octahedral (eight equilateral triangular faces) crystals and man-made diamonds crystals grow with both octahedral and cubic (six equivalent square faces) crystals.
Cube faces grow more quickly than octahedral faces. They are preserved on synthetic diamonds, but they are not preserved on natural diamonds.
Diamonds grow differently, depending on the growth environment:
Natural diamonds grow outward on the octahedral faces.
HPHT synthetic diamonds grow outward on the octahedral and cube faces.
CVD synthetic diamonds grow mainly upward in one direction (a cube face).
Natural and man-made diamonds can exhibit various inclusions (fractures, breaks, other crystals, hollow tubes) so they are not always diagnostic tools for gem identification.
Man-made diamonds are commonly colorless, near-colorless, light to dark yellow or yellow-brown; they are less commonly blue, pink, red or green. Man-made diamonds can be subjected to the same color treatments as natural diamonds, so any color is possible.
Man-made diamonds can be from low to high clarity.
Colored man-made diamonds and larger man-made diamonds are more often fashioned into a fancy shape to retain more weight from the original crystal. The shape of the crystal also influences the choice of faceting styles.
The simplest take way is that lab-created diamonds have:
Same physical hardness as a mined diamond.
Same optical properties as a mined diamond.
Same Molecular structure as a mined diamond.
Will never have any fluorescence.
Will give you around a 20% bigger diamond for the same budget.
Often a cleaner diamond with less inclusions.
Are completely certified and laser inscribed by the worlds certification laboratories. They even have a money back guarantee, if the stone hasn't been accurately graded.