This study examines the short- and long-term relationships between the Darphane Gold Certificate, a Borsa Istanbul-listed investment instrument backed by physical gold, and the BIST30 index. The primary objective is to analyze whether positive and negative shocks in gold certificate prices generate asymmetric effects on the BIST30 index in both the short and long term. To this end, the Nonlinear Autoregressive Distributed Lag (NARDL) model is applied using weekly data. The findings reveal significant and asymmetric relationships between the gold certificate and the BIST30 index in both time horizons. The differential impacts of positive and negative shocks in terms of magnitude and direction indicate that gold-stock interactions cannot be fully explained by linear models. A key finding is that the Darphane Gold Certificate may serve as a leading and directional indicator for the BIST30. The varying intensity and direction of responses in the stock index to increases and decreases in certificate prices demonstrate that gold’s traditional safe-haven role manifests through a distinct institutional instrument in the Turkish market. In this context, the gold certificate can be considered both a portfolio diversification and risk-hedging tool for investors and an indicator for policymakers to anticipate market volatility. The study contributes theoretically to the literature by analyzing gold-stock relationships through a Turkey-specific financial instrument, while also providing actionable insights and recommendations for policymakers and investors to monitor and predict market volatility. Ultimately, the study underscores that gold’s role should be reconceptualized as a context- and instrument-dependent phenomenon rather than a universal one.