URL query considered duplicate content?

[BlazeSunglass]

I have a Magento site.  In order to reduce duplicate content for products of the same style but with different colours I have combined them on to 1 product page.

I would like to allow the pictures to be dynamic, i.e. allow a user to search for a colour and all the products that offer that colour appear in the results, but I dont want the default product image shown but the product image for that colour applying to the query.

Therefore to do this I have to append a query string to the end of the URL to produce this result:

www.website.com/category/product-name.html?=red

My question is, will the query variations then be picked up as duplicate content:

• www.website.com/category/product-name.html
• www.website.com/category/product-name.html?=red
• www.website.com/category/product-name.html?=yellow

Google suggest it has contingencies in its algorithm and I will not be penalised:

http://googlewebmastercentral.blogspot.co.uk/2007/09/google-duplicate-content-caused-by-url.html

But other sources suggest this is not accurate.  Note the article was written in 2007.

[BlazeSunglass]

Thanks for your response.

I am already employing the rel=canonical tag, however I didnt realise I could use Google's Webmaster tools.

Ensuring the sitemap is correct will also contribute to clustering the appended different queries as I understand.

Yes I forgot the variable when typing the example url & query out!

Thanks.

[DMGoo]

You can use the ignore URL parameters in WMT to stop duplicate pages being indexed, however in the URLs you have provided your query string doesnt use variables! if the URLs were of the following format:

www.website.com/category/product-name.html?colour=red

you could use the WMT URL params tool to ignore the "colour" variable.

I would also recommend using the rel=canonical tag on the product-name.html pages:

So the canonical tag on the  www.website.com/category/product-name.html?=red URL would be