Digital pathology is transforming diagnostic workflows by enabling the interpretation of whole-slide images on digital displays, offering advantages in remote diagnostics, efficiency, and integration with computational tools. However, diagnostic reliability depends not only on scanner and software quality but also on the performance of the display systems used for image review, as well as on environmental and ergonomic factors. This study evaluated the impact of display quality on diagnostic accuracy by comparing a medical-grade, professional-grade, and consumer-grade display against conventional light microscopy. Nineteen hematoxylin and eosin (H&E) and 19 immunohistochemistry (IHC) slides were assessed by two board-certified pathologists across all modalities. The medical-grade display achieved perfect concordance with microscopy for H&E slides and was rated highest for image clarity, color fidelity, and luminance stability. In contrast, the professional- and consumer-grade displays showed lower concordance (85–95%) and received inferior subjective evaluation. For IHC slides, both observers achieved 100% concordance for HER2 and AMACR markers across all displays. One discordant MLH1 case was noted on the medical-grade display for one observer out of five cases. Although MLH1 is consistently analyzed alongside other MSI markers, this isolated discrepancy precludes firm conclusions about display performance for this marker. These findings highlight the importance of clinically validated displays with automated calibration and quality assurance mechanisms to ensure consistent diagnostic performance. As digital pathology becomes increasingly integrated with remote workflows, establishing minimum performance standards for display systems will be essential to safeguard diagnostic accuracy, reproducibility, and patient safety in clinical practice.