what am i?

I came onto the scene on 1977.

When I was young, I was 

yellow

♺

& full of —'s.

Now, I follow the rainbow:

Pastel ♺ ♺ ♺

Neon ♺ ♺ ♺

Electric ♺ ♺ ♺

Translucent   ♺  

in many shapes ♥ ◊ ✩

& sizes ☃ ☃ ☃ TwitterKeys

& I even pop up  EmoFaces

I have become a fashion statement kiss markringgem stoneF

Facebook Symbols 

& an art icon  🎇 

Twitter Symbols 

but I never leave a mess where I have been 

What am I?