Fluorescence, bi-colour and colour changing of lab created gemstones?

[Double E]

Lab created stones can come with these characteristics right? Is it rare or harder to create? It seems rarely found or mentioned.

 

[Bron357]

Many lab created gemstones are made of the exact same chemical composition as natural, from the ground, gemstones. Therefore aside from the lack of natural inclusions (nature is rarely perfect) and/or microscopic traits like curved striae or air bubbles typical of lab grown, they look and behave exactly the same.
Lab grown ruby (red corundum) will fluoresce under UV light just as natural does.
The three main lab grown materials are corundum, spinel and topaz. They can be coloured with chemical additives during creation to resemble the many varieties and colours of gems they imitate. Sometimes treatments include coatings or irradiation or even heat quenching to produce internal cracks that resemble those found in natural gems. Synthetic emerald is one such example of this.
Some lab created gemstones have the “look” of the material being imitated by aren’t of the same chemical composition. A type of Synthetic Alexandrite that was popular (it never showed the correct colour change though) was lab grown corundum and not chrysoberyl.
More modern lab created Alexandrite does show the “traditional” green in daylight, purple red under incandescent but many would argue the colours still seem unnatural.
The level of sophistication and techniques for creating gemstones that are virtually indistinguishable from natural has progressed immensely in the past decade. Lab grown diamonds now exist. With these improvements in lab grown gems the need for reputable and reliable certification to ensure “from the earth origin” has likewise increased. Even natural gemstones can now be subtly altered and improved to increase their value (flux filling, diffusion) so again reliable and reputable certification is recommended.

 

[Double E]

Many lab created gemstones are made of the exact same chemical composition as natural, from the ground, gemstones. Therefore aside from the lack of natural inclusions (nature is rarely perfect) and/or microscopic traits like curved striae or air bubbles typical of lab grown, they look and behave exactly the same.
Lab grown ruby (red corundum) will fluoresce under UV light just as natural does.
The three main lab grown materials are corundum, spinel and topaz. They can be coloured with chemical additives during creation to resemble the many varieties and colours of gems they imitate. Sometimes treatments include coatings or irradiation or even heat quenching to produce internal cracks that resemble those found in natural gems. Synthetic emerald is one such example of this.
Some lab created gemstones have the “look” of the material being imitated by aren’t of the same chemical composition. A type of Synthetic Alexandrite that was popular (it never showed the correct colour change though) was lab grown corundum and not chrysoberyl.
More modern lab created Alexandrite does show the “traditional” green in daylight, purple red under incandescent but many would argue the colours still seem unnatural.
The level of sophistication and techniques for creating gemstones that are virtually indistinguishable from natural has progressed immensely in the past decade. Lab grown diamonds now exist. With these improvements in lab grown gems the need for reputable and reliable certification to ensure “from the earth origin” has likewise increased. Even natural gemstones can now be subtly altered and improved to increase their value (flux filling, diffusion) so again reliable and reputable certification is recommended.

Thanks very much for providing me such detailed information, it's definitely helpful~

For the lab Alexandrite part, do you mean that there are practices from lab stone suppliers that that advertise the stone as Alex but in fact it's not? Am I reasonable to assume similar practices is being carried-out also for other stone types?

Actually another aspect which confuses me is that whether lab stones are "treated" as you mentioned. Or How should we define "treated" for lab stones? For example, is that like all stuffs done within the crystal growth process is not claimed to be "treated", but only those done after growth process? And how common are these post-growth treatments, and how we consumers identify the gem we are buying has undergone treatment or not? Don't get me wrong, I do believe in those trusted vendors here in PS, just really want to have a better understanding.