All unique and set items have specific colors & graphics, for example: Tal Rasha's Guardianship (Lacquered Plate)
Armors found in-game may vary by color, since certain affixes add palette shifts, but the basic graphics never change.
When it comes to rare items, the color of the item is dependent on the modifiers of the item. Grey items seem to take their colors from the first inserted gem (e.g., ruby = red)

Heavy and medium armors and shields reduce movement speed. Heavier armor drains stamina faster and reduces run/walk speed, in this case:
By armors (and shields) weight:
•Light = no running speed/stamina penalty
•Medium = 5% penalty (5% speed decrease & faster stamina drain)
•Heavy = 10% penalty (10% speed decrease & faster stamina drain)

Light Shields
Necromancer Shrunken Heads
Paladin Shields
Buckler/Defender/Heater
Small/Round/Luna
Kite/Dragon/Monarch
Bone/Grim/Troll Nest
Spiked/Barbed/Blade Barrier

Medium Shields (5% penalty)
Large/Scutum/Hyperion
Gothic/Ancient/Ward

Heavy Shields (10% penalty)
Tower/Pavise/Aegis


Stamina Loss
25 * (40 * (1 + [ArmorSpeed / 10]) * ItemDrainRate / 256)

where:
ArmorSpeed is the value listed for your currently equipped armor + shield (possibly).
ItemDrainRate is any percentage bonus your items give you to x% Slower Stamina Drain.

An example:
Light Armor + Medium Shield: 25 * (40 * (1 + [0+5 / 10]) / 256) = 25 (60 / 256) = 5,859375 Stamina lost per second.


General conclusions:
If you're having serious problems with stamina, switch to medium or Light Armor and/or Shield.
Aim for light armors (basing on your strength if you are not willing to use the strength bug glitch) unless you're looking for a solid defence increasement (in case you're a caster and you won't need frw).


The glitch
What's a strength/dexterity bug?
It's a glitch that allows you to use certain items without reaching a required strength/dexterity cap.


How to?
First of all you gonna need a specific item(s) with a huge strength/dexterity boost (the higher is better because you won't be needing another items then) or massive amount of strength/dexterity charms.
Let's say we're a barbarian, level 80 (basic barbarian's strength is 30), we're using mediums: Annihilus(+15 all atributes), Hellfire Torch (+15), Enigma(+0.75 Strength Per Character Level, so in our case it's 0.75x80=60)[let's say it's a mage plate, but it's not important right now, we can glitch enigma as well] and we want to equip Stormshield (Required Strength: 156). We've got only 30+15+15+60(=120 total), so it means we're missing 36 str points, BUT because shield itself gives +30 To Strength(after we equip), we're missing only +6 strength points! At this stage we need to equip a random item(s)/charm(s) that will add + 36 str (30 for a shield compensation, 6 permanent, because it's missing), finally equip our shield and remove (/stash) a random item(/s) [+30] afterwards and we'll be still able to wear the shield as long as we do not unequip it.

Dangers of glitching
In case you die you won't be able to equip the glitched item and it will remain in your body if you don't have free space in your equipment. If you die second time there will be two bodies and if you rejoin, only 1 body will be spawned (the one with more gold value items), so that means your items may be very easily lost.



Credits:
Previous (outdated) thread: Armor Appearence And Information > C What Every Armor Looks Like On Chars!
Special thanks for correcting and approving goes to: RaveTheGo