What are the crest colors and how much of it do I need for each stage?

There are crests on the profile page. What colors are there and how much takedowns/kills/wins do I need for each stage of it? (This question is also for the dominion crests)

Images of the crests would be appreciated.

The colors range from none, to Bronze, Silver, Gold, then Platinum. What these count are the total number of Take-downs (which is a summary of your kills, assists, and destroyed towers), Monster/Minion Kills, and Wins in Classic, and Take-downs, Points Captured/Neutralized, and Wins in Dominion.

The thresholds are as follows:

None, this shows in your profile if you do not meet the minimum thresholds for Bronze.

_{(source: wikia.com)}

Bronze

Classic

• 100 Takedowns
• 2,000 Monster/Minion Kills
• 5 Wins

Dominion

• 100 Takedowns
• 100 Points captured/neutralized
• 5 Wins

ARAM

• 100 Takedowns
• 5 Towers Destroyed
• 5 Wins

_{(source: wikia.com)}

Silver

Classic

• 1,000 Takedowns
• 10,000 Monster/Minion Kills
• 25 Wins

Dominion

• 500 Takedowns
• 250 Points captured/neutralized
• 25 Wins

ARAM

• 500 Takedowns
• 25 Towers Destroyed
• 25 Wins

_{(source: wikia.com)}

Gold

Classic

• 2,500 Takedowns
• 50,000 Monster/Minion Kills
• 100 Wins

Dominion

• 2,500 Takedowns
• 500 Points captured/neutralized
• 100 Wins

ARAM

• 2,500 Takedowns
• 100 Towers Destroyed
• 100 Wins

_{(source: wikia.com)}

Platinum

Classic

• 5,000 Takedowns
• 100,000 Monster/Minion Kills
• 300 Wins

Dominion

• 5,000 Takedowns
• 1,000 Points captured/neutralized
• 300 Wins

ARAM

• 5,000 Takedowns
• 200 Towers Destroyed
• 300 Wins (unconfirmed)

_{(source: wikia.com)}

Diamond

Classic

• 10,000 Takedowns
• 200,000 Monster/Minion Kills
• 600 Wins

Dominion

• 10,000 Takedowns
• 5,000 Points captured/neutralized
• 600 Wins

ARAM

• 10,000 Takedowns
• 500 Towers Destroyed (unconfirmed)
• 600 Wins

Sourced from the LoL wiki