I have seen, own and viewed jade jewelry for decades but I am not a jeweler nor a rock expert.  However if you actually want to buy a piece of jade jewelry online and are willing to take a chance on buying it from overseas, be forewarned that many of the items listed as "jade" are not jade, nor are they authentically  the "color" as portrayed.  Jade from China used for jewelry is usually Jadeite, which is very hard and has a high luster. jadeite is rated aprox. 6.5 to 7 on the Mohs scale of hardness.

Although Jadeite comes in many colors and is a natural stone, it usually does not appear as bright pink, purple or bright lavender, blue, red,  green, or even pink.  It is possible that it could appear as a bright green (in the USA many like to call it imperial or apple green) but it is nearly impossible to find such a beautiful green piece of jade with no inclusions for little money. 
As an example, an exceptional green, translucent gorgeous green jade bangle bracelet with no inclusions was seen in a San Francisco jewelry store; it was $10,000.

There are many other types of stone used, which could resemble jade to the layperson, such as Serpentine (often used for architecture), Bowenite (a form of Serpentine), Aventurine (a form of quartz), Chrysoprase (very uniform color, pretty green, high luster), Carnelian (very uniform orange-red color, no crystalline quality), Jasper (agate form, often known as bloodstone), Rhodonite (an attractive pink color, usually has mottled pink/gray), and dyed stones(such as alabaster, marble, onyx which is dyed to look like jade.)

In general, if a colored piece of jade is extremely bright and dazzling with the affordable price to match, it is not authentic (that is, it has been color enhanced.)  If it is described as pink, blue, purple, orange, it is probably not authentic either.

The pink necklace above is likely rose quartz but it was sold as pink "jade." the bracelet on the right is likely genuine. Notice the colors are not necessarily vibrant. 

the multi-colored pendant piece below is probably real and oftentimes smaller pieces will contain more than several colors. Many smaller pieces of jade will have intricate carvings or tiny holes drilled through, this is often used to thread onto hats for children. Most of these pieces are genuine.  

The piece below is likely color enhanced and is uniformly very purple, too much so in my opinion.

The one piece bangle below has several colors which are not uniform in size, pattern, or even location. this is 99.9% real color in my opinion. 

Tests have been done on dyed jade in the past; in some instances, the jade remained colorfast even as long as 10 years. In other testing when placed outside in sunlight directly for more than 6 months, the color faded, leaving a very unattractive piece of stone.  Some have even boiled the stones in oil (like in a french fry boiler) and they retained their dyed coloring.  Reputable dealers of jade do not sell dyed pieces; if for some reason they do, such pieces would invariably state that they are color enhanced. Use of a chelsea filter may be able to show evidence of dyed jade. (I am not positive if this would indicate bleaching or polymer inclusion.)

We have seen jade sold on the home shopping network, and usually they mention that the color has been enhanced. It is a misrepresentation in my opinion, to not tell the public if an item has been color enhanced, and to label a stone jade when, in fact, it is not jade at all.   A natural colored piece of jade may become darker by wearing it consistently, and it may also lose some luster. (Of course it can be polished like any natural stone)   For example, a green and white jade bracelet may become more green if it is consistently worn.