Here's the code for that block
<?php
/*
* Customer reviews of Argento at homepage
*
*/
$product_id = "4";
$obj = Mage::getModel('catalog/product');
$product = $obj->load($product_id); // Enter your Product Id in $product_id
$storeId = Mage::app()->getStore()->getId();
Mage::getModel('review/review')->getEntitySummary($product, $storeId);
$ratingSummary = $product->getRatingSummary();
$formattedRatingSummary = ($product->getRatingSummary()->getRatingSummary() * 5) / 100;
$reviewsCount = $product->getRatingSummary()->getReviewsCount();
// echo '<span>'. $formattedRatingSummary . '</span> out of 5 based on ' . $reviewsCount . ' ratings.';
?>
<div xmlns:v="http://rdf.data-vocabulary.org/#" typeof="v:Review-aggregate">
<div>
<span rel="v:rating">
<span typeof="v:Rating">
<span property="v:average"><?php echo $formattedRatingSummary; ?></span> out of
<span property="v:best">5</span>
</span>
</span>
<span property="v:votes">
<span>based on </span><?php echo $reviewsCount ?> ratings.
</span>
<span property="v:count"></span>
<span property="v:itemreviewed" style="display:none">Argento Theme</span>Read
<a href="<?php echo $this->getUrl('review/product/list/id/4/');?>">client reviews.</a>
</div>
</div>
Wheer id=4 is the id of product