When evaluating Frozen Illex Squid (Illex argentinus), you must prioritize freshness and processing standards. Look for a natural reddish-brown skin color; a pale or yellowish tint may indicate oxidation or poor temperature control. The meat should be firm and elastic upon thawing. Ensure the glazing percentage (ice coating) is clearly defined, typically ranging from 0% to 20%, as this directly impacts your net weight and cost-efficiency. Additionally, verify the size grading (e.g., 100-150g, 150-200g, or 200-300g) to ensure it meets your specific market or processing needs.