Adding new variant option via api by Aaron Mashburn

I have an existing series of products with one variant option, "Size". Using the API, I am attempting to add a 2nd option, "Color". Below is an example of the array I am sending, using PUT /admin/products/#{id}.json to modify an existing product. HOWEVER, if I send the same information using POST /admin/products.json (create a new product) a new product is created with BOTH options, with no errors.

A couple notes:

1. I looked through the admin interface for clues, creating a new variant option requires "defaultValue" with the option name, so as you see in the array, I have also tried adding that value without success.

2. The return info from shopify is simply all the product information, indicating a successful update.

So, (tl,dr) What is the best way to update an existing product by adding the new variant option, "Size"?

RESArray
(
    [id] => 90230465
    [created_at] => 2012-04-04 10:55:03
    [handle] => my-product-handle
    [title] => My Product
    [product_type] => Tops
    [vendor] => My Online Store
    [body_html] => 
    [tags] => blue, shirt
    [options] => Array
        (
            [0] => Array
                (
                    [id] => 107709133
                    [position] => 1
                    [product_id] => 90230465
                    [name] => Size
                )

            [1] => Array
                (
                    [id] => 1403143717
                    [name] => Color
                    [position] => 2
                    [product_id] => 90230465
                    [defaultValue] => Blue
                )

        )

    [variants] => Array
        (
            [0] => Array
                (
                    [id] => 211236403
                    [product_id] => 90230465
                    [position] => 1
                    [barcode] => 
                    [created_at] => 2012-04-04 10:55:03
                    [fulfillment_service] => manual
                    [inventory_management] => shopify
                    [inventory_policy] => deny
                    [requires_shipping] => true
                    [taxable] => 1
                    [title] => Small / Blue
                    [sku] => BNV-F720003BS
                    [inventory_quantity] => 0
                    [price] => 29.00
                    [grams] => 0
                    [compare_at_price] => 
                    [option1] => Small
                    [option2] => Blue
                    [option3] => 
                    [updated_at] => 2014-03-14 01:26:12
                )

            [1] => Array
                (
                    [id] => 211243301
                    [product_id] => 90230465
                    [position] => 2
                    [barcode] => 
                    [created_at] => 2012-04-04 12:56:38
                    [fulfillment_service] => manual
                    [inventory_management] => shopify
                    [inventory_policy] => deny
                    [requires_shipping] => true
                    [taxable] => 1
                    [title] => Medium / Blue
                    [sku] => BNV-F720003BM
                    [inventory_quantity] => 0
                    [price] => 22.00
                    [grams] => 0
                    [compare_at_price] => 29.00
                    [option1] => Medium
                    [option2] => Blue
                    [option3] => 
                    [updated_at] => 2014-03-14 01:26:12
                )

            [2] => Array
                (
                    [id] => 211243343
                    [product_id] => 90230465
                    [position] => 3
                    [barcode] => 
                    [created_at] => 2012-04-04 12:57:00
                    [fulfillment_service] => manual
                    [inventory_management] => shopify
                    [inventory_policy] => deny
                    [requires_shipping] => true
                    [taxable] => 1
                    [title] => Large / Blue
                    [sku] => BNV-F720003BL
                    [inventory_quantity] => 0
                    [price] => 29.00
                    [grams] => 0
                    [compare_at_price] => 
                    [option1] => Large
                    [option2] => Blue
                    [option3] => 
                    [updated_at] => 2014-03-14 01:26:12
                )

        )

    [published] => false
    [updated_at] => 2014-03-14 01:26:12
    [published_scope] => global
    [template_suffix] => 
)