Woocommerce Product Variation Attribute Values [on hold]

In Woocommerce 2.2.10 I have a product variation:

$variation = new WC_Product_Variation($variation_id);

and I want to get the attributes:

$attributes = $variation->get_variation_attributes();

returns

$attributes = array (
    'attribute_color' => "mint-green",
    'attribute_size' => "small"
)

But on the front-end in Woocommerce admin the attribute text as displayed in the color and size options is "Mint Green" and "Small", as opposed to the option values ("mint-green", "small"), which are returned by get_variation_attributes():

i.e.

<select name="attribute_color[0]">
   <option value="">Any Color...</option>
   <option selected="selected" value="mint-green">mint green</option>
</select>
<select name="attribute_size[0]">
   <option value="">Any Size...</option>
   <option selected="selected" value="small">Small</option>
</select>

Can I get product attributes in their original formatting?